diff --git a/zh-cn/application-dev/internationalization/i18n-guidelines.md b/zh-cn/application-dev/internationalization/i18n-guidelines.md
index 0c36d307e930eaedd8278b4878c093a69676592d..8bf711e99801cff4cfbdc58b81a6f4b74722a041 100644
--- a/zh-cn/application-dev/internationalization/i18n-guidelines.md
+++ b/zh-cn/application-dev/internationalization/i18n-guidelines.md
@@ -49,7 +49,7 @@
    ```js
    try {
       I18n.System.setSystemLanguage("en"); // 将系统语言设置为 "en"
-      var language = I18n.System.getSystemLanguage(); // language = "en"
+      let language = I18n.System.getSystemLanguage(); // language = "en"
    } catch(error) {
       console.error(`call i18n.System interface failed, error code: ${error.code}, message: ${error.message}`)
    }
@@ -63,7 +63,7 @@
    ```js
    try {
       I18n.System.setSystemRegion("CN"); // 将系统国家设置为 "CN"
-      var region = I18n.System.getSystemRegion(); // region = "CN"
+      let region = I18n.System.getSystemRegion(); // region = "CN"
    } catch(error) {
       console.error(`call i18n.System interface failed, error code: ${error.code}, message: ${error.message}`)
    }
@@ -77,7 +77,7 @@
    ```js
    try {
       I18n.System.setSystemLocale("zh-Hans-CN"); // 将系统Locale设置为 "zh-Hans-CN"
-      var locale = I18n.System.getSystemLocale(); // locale = "zh-Hans-CN"
+      let locale = I18n.System.getSystemLocale(); // locale = "zh-Hans-CN"
    } catch(error) {
       console.error(`call i18n.System interface failed, error code: ${error.code}, message: ${error.message}`)
    }
@@ -88,9 +88,8 @@
    调用isRTL接口获取Locale的语言是否为从右到左语言。
 
    ```js
-   
    try {
-      var rtl = I18n.isRTL("zh-CN"); // rtl = false
+      let rtl = I18n.isRTL("zh-CN"); // rtl = false
       rtl = I18n.isRTL("ar"); // rtl = true
    } catch(error) {
       console.error(`call i18n.System interface failed, error code: ${error.code}, message: ${error.message}`)
@@ -103,10 +102,9 @@
    调用is24HourClock接口来判断当前是否打开系统24小时制设置。
 
    ```js
-   
    try {
       I18n.System.set24HourClock(true);
-      var hourClock = I18n.System.is24HourClock(); // hourClock = true
+      let hourClock = I18n.System.is24HourClock(); // hourClock = true
    } catch(error) {
       console.error(`call i18n.System interface failed, error code: ${error.code}, message: ${error.message}`)
    }
@@ -117,12 +115,11 @@
    调用getDisplayLanguage接口获取某一语言的本地化表示。其中，language表示待本地化显示的语言，locale表示本地化的Locale，sentenceCase结果是否需要首字母大写。
 
    ```js
-   
    try {
-      var language = "en";
-      var locale = "zh-CN";
-      var sentenceCase = false;
-      var localizedLanguage = I18n.System.getDisplayLanguage(language, locale, sentenceCase); // localizedLanguage = "英语"
+      let language = "en";
+      let locale = "zh-CN";
+      let sentenceCase = false;
+      let localizedLanguage = I18n.System.getDisplayLanguage(language, locale, sentenceCase); // localizedLanguage = "英语"
    } catch(error) {
       console.error(`call i18n.System interface failed, error code: ${error.code}, message: ${error.message}`)
    }
@@ -133,12 +130,11 @@
    调用getDisplayCountry接口获取某一国家的本地化表示。其中，country表示待本地化显示的国家，locale表示本地化的Locale，sentenceCase结果是否需要首字母大写。
 
    ```js
-   
    try {
-      var country = "US";
-      var locale = "zh-CN";
-      var sentenceCase = false;
-      var localizedCountry = I18n.System.getDisplayCountry(country, locale, sentenceCase); // localizedCountry = "美国"
+      let country = "US";
+      let locale = "zh-CN";
+      let sentenceCase = false;
+      let localizedCountry = I18n.System.getDisplayCountry(country, locale, sentenceCase); // localizedCountry = "美国"
    } catch(error) {
       console.error(`call i18n.System interface failed, error code: ${error.code}, message: ${error.message}`)
    }
@@ -151,8 +147,8 @@
    ```js
    
    try {
-      var languageList = I18n.System.getSystemLanguages();  // languageList = ["en-Latn-US", "zh-Hans"]
-      var countryList = I18n.System.getSystemCountries("zh"); // countryList = ["ZW", "YT", ..., "CN", "DE"], 共240个国家和地区
+      let languageList = I18n.System.getSystemLanguages();  // languageList = ["en-Latn-US", "zh-Hans"]
+      let countryList = I18n.System.getSystemCountries("zh"); // countryList = ["ZW", "YT", ..., "CN", "DE"], 共240个国家和地区
    } catch(error) {
       console.error(`call i18n.System interface failed, error code: ${error.code}, message: ${error.message}`)
    }
@@ -164,7 +160,7 @@
    
    ```js
    try {
-      var isSuggest = I18n.System.isSuggested("zh", "CN"); // isSuggest = true
+      let isSuggest = I18n.System.isSuggested("zh", "CN"); // isSuggest = true
    } catch(error) {
       console.error(`call i18n.System interface failed, error code: ${error.code}, message: ${error.message}`)
    }
@@ -181,10 +177,10 @@
    ```js
    try {
       I18n.System.addPreferredLanguage("en-GB", 0); // 将"en-GB"设置为系统偏好语言列表的第一个语言
-      var list = I18n.System.getPreferredLanguageList(); // 获取当前系统偏好语言列表 list = ["en-GB", ...]
+      let list = I18n.System.getPreferredLanguageList(); // 获取当前系统偏好语言列表 list = ["en-GB", ...]
       I18n.System.removePreferredLanguage(list.length - 1); // 移除当前系统偏好语言列表中的最后一个偏好语言
-      var firstPreferredLanguage = I18n.System.getFirstPreferredLanguage(); // firstPreferredLanguage = "en-GB"
-      var appPreferredLanguage = I18n.System.getAppPreferredLanguage(); // 当应用中包含 "en-GB"资源时，应用偏好语言为"en-GB"
+      let firstPreferredLanguage = I18n.System.getFirstPreferredLanguage(); // firstPreferredLanguage = "en-GB"
+      let appPreferredLanguage = I18n.System.getAppPreferredLanguage(); // 当应用中包含 "en-GB"资源时，应用偏好语言为"en-GB"
    } catch(error) {
       console.error(`call i18n.System interface failed, error code: ${error.code}, message: ${error.message}`)
    }
@@ -199,7 +195,7 @@
 ```js
 try {
    I18n.System.setUsingLocalDigit(true); // 打开本地化数字开关
-   var status = I18n.System.getUsingLocalDigit(); // status = true
+   let status = I18n.System.getUsingLocalDigit(); // status = true
 } catch(error) {
    console.error(`call i18n.System interface failed, error code: ${error.code}, message: ${error.message}`)
 }
@@ -239,7 +235,7 @@ try {
    调用getCalendar接口获取指定locale和type的时区对象（i18n为导入的模块）。其中，type表示合法的日历类型，目前合法的日历类型包括："buddhist", "chinese", "coptic", "ethiopic", "hebrew", "gregory", "indian", "islamic_civil", "islamic_tbla", "islamic_umalqura", "japanese", "persian"。当type没有给出时，采用区域默认的日历类型。
 
    ```js
-   var calendar = I18n.getCalendar("zh-CN", "chinese"); // 创建中文农历日历
+   let calendar = I18n.getCalendar("zh-CN", "chinese"); // 创建中文农历日历
    ```
 
 3. 设置日历对象的时间。
@@ -247,9 +243,9 @@ try {
      调用setTime接口设置日历对象的时间。setTime接口接收两种类型的参数。一种是传入一个Date对象，另一种是传入一个数值表示从1970.1.1 00:00:00 GMT逝去的毫秒数。
 
    ```js
-   var date1 = new Date();
+   let date1 = new Date();
    calendar.setTime(date1);
-   var date2 = 1000;
+   let date2 = 1000;
    calendar.setTime(date2);
    ```
 
@@ -267,7 +263,7 @@ try {
 
    ```js
    calendar.setTimeZone("Asia/Shanghai");
-   var timezone = calendar.getTimeZone();  // timezone = "China Standard Time"
+   let timezone = calendar.getTimeZone();  // timezone = "China Standard Time"
    ```
 
 6. 设置、获取日历对象的一周起始日。
@@ -276,7 +272,7 @@ try {
 
    ```js
    calendar.setFirstDayOfWeek(1);
-   var firstDayOfWeek = calendar.getFirstDayOfWeek(); // firstDayOfWeek = 1
+   let firstDayOfWeek = calendar.getFirstDayOfWeek(); // firstDayOfWeek = 1
    ```
 
 7. 设置、获取日历对象第一周的最小天数。
@@ -284,14 +280,14 @@ try {
 
    ```js
    calendar.setMinimalDaysInFirstWeek(3);
-   var minimalDaysInFirstWeek = calendar.getMinimalDaysInFirstWeek(); // minimalDaysInFirstWeek = 3
+   let minimalDaysInFirstWeek = calendar.getMinimalDaysInFirstWeek(); // minimalDaysInFirstWeek = 3
    ```
 
 8. 获取日历对象的本地化显示。
    调用getDisplayName来获取日历对象的本地化显示。
 
    ```js
-   var localizedName = calendar.getDisplayName("zh-CN"); // localizedName = "农历"
+   let localizedName = calendar.getDisplayName("zh-CN"); // localizedName = "农历"
    ```
 
 9. 判断某一个日期是否为周末。
@@ -299,8 +295,8 @@ try {
    调用isWeekend接口来判断输入的Date是否为周末。
 
    ```js
-   var date = new Date(2022, 12, 12, 12, 12, 12);
-   var weekend = calendar.isWeekend(date); // weekend = false
+   let date = new Date(2022, 12, 12, 12, 12, 12);
+   let weekend = calendar.isWeekend(date); // weekend = false
    ```
 
 ## 电话号码格式化
@@ -329,7 +325,7 @@ try {
    调用PhoneNumberFormat的构造函数来实例化电话号码格式化对象，需要传入电话号码的国家代码及格式化选项。其中，格式化选项是可选的，包括style选项，该选项的取值包括："E164", "INTERNATIONAL", "NATIONAL", "RFC3966"。
 
    ```js
-   var phoneNumberFormat = new I18n.PhoneNumberFormat("CN", {type: "E164"});
+   let phoneNumberFormat = new I18n.PhoneNumberFormat("CN", {type: "E164"});
    ```
 
 3. 判断电话号码格式是否正确。
@@ -337,7 +333,7 @@ try {
      调用isValidNumber接口来判断输入的电话号码的格式是否正确。
 
    ```js
-   var validNumber = phoneNumberFormat.isValidNumber("15812341234"); // validNumber = true
+   let validNumber = phoneNumberFormat.isValidNumber("15812341234"); // validNumber = true
    ```
 
 4. 电话号码格式化。
@@ -345,7 +341,7 @@ try {
      调用电话号码格式化对象的format接口来对输入的电话号码进行格式化。
 
    ```js
-   var formattedNumber = phoneNumberFormat.format("15812341234"); // formattedNumber = "+8615812341234"
+   let formattedNumber = phoneNumberFormat.format("15812341234"); // formattedNumber = "+8615812341234"
    ```
 
 ## 度量衡转换
@@ -371,12 +367,12 @@ try {
    调用[unitConvert](../reference/apis/js-apis-i18n.md#unitconvert9)接口实现度量衡单位转换，并进行格式化显示的功能。
 
    ```js
-   var fromUnit = {unit: "cup", measureSystem: "US"};
-   var toUnit = {unit: "liter", measureSystem: "SI"};
-   var number = 1000;
-   var locale = "en-US";
-   var style = "long";
-   var converttedUnit = I18n.I18NUtil.unitConvert(fromUnit, toUnit, number, locale, style); // converttedUnit = "236.588 liters"
+   let fromUnit = {unit: "cup", measureSystem: "US"};
+   let toUnit = {unit: "liter", measureSystem: "SI"};
+   let number = 1000;
+   let locale = "en-US";
+   let style = "long";
+   let converttedUnit = I18n.I18NUtil.unitConvert(fromUnit, toUnit, number, locale, style); // converttedUnit = "236.588 liters"
    ```
 
 ## 字母表索引
@@ -406,7 +402,7 @@ try {
 
 
    ```js
-   var indexUtil = I18n.getInstance("zh-CN");
+   let indexUtil = I18n.getInstance("zh-CN");
    ```
 
 3. 获取索引列表。
@@ -414,7 +410,7 @@ try {
      调用getIndexList接口来获取当前Locale对应的字母表索引列表。
 
    ```js
-   var indexList = indexUtil.getIndexList(); // indexList = ["...", "A", "B", "C", ..., "X", "Y", "Z", "..."]
+   let indexList = indexUtil.getIndexList(); // indexList = ["...", "A", "B", "C", ..., "X", "Y", "Z", "..."]
    ```
 
 4. 增加新的索引。
@@ -430,8 +426,8 @@ try {
      调用getIndex接口来获取某一字符串对应的字母表索引。
 
    ```js
-   var text = "access index";
-   var index = indexUtil.getIndex(text); // index = "A"
+   let text = "access index";
+   let index = indexUtil.getIndex(text); // index = "A"
    ```
 
 ## 获取文本断点位置
@@ -466,8 +462,8 @@ try {
    调用getLineInstance接口来实例化断行对象。
 
    ```js
-   var locale = "en-US"
-   var breakIterator = I18n.getLineInstance(locale);
+   let locale = "en-US"
+   let breakIterator = I18n.getLineInstance(locale);
    ```
 
 3. 设置、访问要断行处理的文本。
@@ -475,9 +471,9 @@ try {
    调用setLineBreakText接口和getLineBreakText接口来设置、访问要断行处理的文本。
 
    ```js
-   var text = "Apple is my favorite fruit";
+   let text = "Apple is my favorite fruit";
    breakIterator.setLineBreakText(text);
-   var breakText = breakIterator.getLineBreakText();  // breakText = "Apple is my favorite fruit"
+   let breakText = breakIterator.getLineBreakText();  // breakText = "Apple is my favorite fruit"
    ```
 
 4. 获取断行对象当前的位置。
@@ -485,7 +481,7 @@ try {
    调用current接口来获取断行对象在当前处理文本中的位置。
 
    ```js
-   var pos = breakIterator.current(); // pos = 0
+   let pos = breakIterator.current(); // pos = 0
    ```
 
 5. 设置断行对象的位置。
@@ -493,15 +489,15 @@ try {
    系统提供了很多接口可以用于调整断行对象在处理文本中的位置，包括first, last, next, previous, following。
 
    ```js
-   var firstPos = breakIterator.first(); // 将断行对象设置到第一个分割点的位置，即文本的起始位置；firstPos = 0
-   var lastPos = breakIterator.last();  // 将断行对象设置到最后一个分割点的位置，即文本末尾的下一个位置；lastPos = 26
+   let firstPos = breakIterator.first(); // 将断行对象设置到第一个分割点的位置，即文本的起始位置；firstPos = 0
+   let lastPos = breakIterator.last();  // 将断行对象设置到最后一个分割点的位置，即文本末尾的下一个位置；lastPos = 26
    // 将断行对象向前或向后移动一定数量的分割点。
    // 当传入正数时，向后移动；当传入负数时，向前移动；当未传入数值时，则向后移动一个位置；
    // 当移动超出了文本的长度范围，则返回-1；
-   var nextPos = breakIterator.next(-2); // nextPos = 12
-   var previousPos = breakIterator.previous();  // 将断行对象向前移动向前移动一个分割点，当超出文本长度范围时返回-1； previousPos = 9
+   let nextPos = breakIterator.next(-2); // nextPos = 12
+   let previousPos = breakIterator.previous();  // 将断行对象向前移动向前移动一个分割点，当超出文本长度范围时返回-1； previousPos = 9
    // 将断行对象移动到offset指定位置的后面一个分割点。如果offset所指定的位置的下一个分割点超出了文本的长度范围，则返回-1；
-   var followingPos = breakIterator.following(10); // followingPos = 12
+   let followingPos = breakIterator.following(10); // followingPos = 12
    ```
 
 6. 判断某个位置是否为分割点。
@@ -509,7 +505,7 @@ try {
    调用isBoundary接口来判断一个接口是否为分割点；如果该位置是分割点，则返回true，并且将断行对象移动到该位置；如果该位置不是分割点，则返回false，并且将断行对象移动到该位置后的一个分割点。
 
    ```js
-   var isboundary = breakIterator.isBoundary(5); // isboundary = false
+   let isboundary = breakIterator.isBoundary(5); // isboundary = false
    ```
 
 ## 获取时区
@@ -543,16 +539,16 @@ try {
    调用getTimeZone接口来获取时区对象。
 
    ```js
-   var timezone = I18n.getTimeZone(); // 使用默认参数可以获取系统时区对象。
+   let timezone = I18n.getTimeZone(); // 使用默认参数可以获取系统时区对象。
    ```
 
    获取时区ID、本地化显示、时区偏移量、某一时刻的时区偏移量信息。
    
    ```js
-   var timezoneID = timezone.getID(); // timezoneID = "Asia/Shanghai"
-   var timezoneDisplayName = timezone.getDisplayName(); // timezoneDisplayName = "中国标准时间"
-   var rawOffset = timezone.getRawOffset(); // rawOffset = 28800000
-   var offset = timezone.getOffset(new Date()); // offset = 28800000
+   let timezoneID = timezone.getID(); // timezoneID = "Asia/Shanghai"
+   let timezoneDisplayName = timezone.getDisplayName(); // timezoneDisplayName = "中国标准时间"
+   let rawOffset = timezone.getRawOffset(); // rawOffset = 28800000
+   let offset = timezone.getOffset(new Date().getTime()); // offset = 28800000
    ```
 
 3. 获取系统支持的时区ID。
@@ -561,9 +557,9 @@ try {
    时区ID列表中的时区ID可以作为getTimeZone接口的参数，来创建TimeZone对象。
 
    ```js
-   var timezoneIDs = I18n.TimeZone.getAvailableIDs(); // timezoneIDs = ["America/Adak", ...]，共包含24个时区ID
-   var timezone = I18n.getTimeZone(timezoneIDs[0]);
-   var timezoneDisplayName = timezone.getDisplayName(); // timezoneDisplayName = "夏威夷-阿留申时间"
+   let timezoneIDs = I18n.TimeZone.getAvailableIDs(); // timezoneIDs = ["America/Adak", ...]，共包含24个时区ID
+   let timezone = I18n.getTimeZone(timezoneIDs[0]);
+   let timezoneDisplayName = timezone.getDisplayName(); // timezoneDisplayName = "夏威夷-阿留申时间"
    ```
 
 4. 获取系统支持的时区城市ID。
@@ -573,10 +569,10 @@ try {
    调用getTimezoneFromCity接口基于时区城市ID创建时区对象。
 
    ```js
-   var zoneCityIDs = I18n.TimeZone.getAvailableZoneCityIDs(); // ["Auckland", "Magadan", ...]
-   var cityDisplayName = I18n.TimeZone.getCityDisplayName(zoneCityIDs[0], "zh-Hans"); // cityDisplayName = "奥克兰(新西兰)"
-   var timezone = I18n.TimeZone.getTimezoneFromCity(zoneCityIDs[0]);
-   var timezoneDisplayName = timezone.getDisplayName(); // timezoneDisplayName = "新西兰时间"
+   let zoneCityIDs = I18n.TimeZone.getAvailableZoneCityIDs(); // ["Auckland", "Magadan", ...]
+   let cityDisplayName = I18n.TimeZone.getCityDisplayName(zoneCityIDs[0], "zh-Hans"); // cityDisplayName = "奥克兰(新西兰)"
+   let timezone = I18n.TimeZone.getTimezoneFromCity(zoneCityIDs[0]);
+   let timezoneDisplayName = timezone.getDisplayName(); // timezoneDisplayName = "新西兰时间"
    ```
 
 ## 获取音译对象
@@ -605,7 +601,7 @@ try {
    每个ID的格式为 source-destination，例如 ASCII-Latin，表示将ASCII转换为Latin的音译ID。
 
    ```js
-   var ids = I18n.Transliterator.getAvailableIDs(); // ids = ["ASCII-Latin", "Accents-Any", ... ]，共支持671个语言
+   let ids = I18n.Transliterator.getAvailableIDs(); // ids = ["ASCII-Latin", "Accents-Any", ... ]，共支持671个语言
    ```
 
 3. 创建音译对象，获取音译字符串。
@@ -614,8 +610,8 @@ try {
    调用transform接口，获取音译字符串。
 
    ```js
-   var transliterator = I18n.Transliterator.getInstance("Any-Latn"); // Any-Latn表示将任意文本转换为Latn文本
-   var transformText = transliterator.transform("你好"); // transformText = "nǐ hǎo "
+   let transliterator = I18n.Transliterator.getInstance("Any-Latn"); // Any-Latn表示将任意文本转换为Latn文本
+   let transformText = transliterator.transform("你好"); // transformText = "nǐ hǎo "
    ```
 
 ## 字符类型判断
@@ -649,56 +645,56 @@ try {
    判断字符是否是数字。
 
    ```js
-   var isDigit = I18n.Unicode.isDigit("1"); // isDigit = true
+   let isDigit = I18n.Unicode.isDigit("1"); // isDigit = true
    isDigit = I18n.Unicode.isDigit("a"); // isDigit = false
    ```
 
    判断字符是否是空格符。
 
    ```js
-   var isSpaceChar = I18n.Unicode.isSpaceChar(" "); // isSpaceChar = true
+   let isSpaceChar = I18n.Unicode.isSpaceChar(" "); // isSpaceChar = true
    isSpaceChar = I18n.Unicode.isSpaceChar("\n"); // isSpaceChar = false
    ```
 
    判断字符是否是空白符。
 
    ```js
-   var isWhitespace = I18n.Unicode.isWhitespace(" "); // isWhitespace = true
+   let isWhitespace = I18n.Unicode.isWhitespace(" "); // isWhitespace = true
    isWhitespace = I18n.Unicode.isWhitespace("\n"); // isWhitespace = true
    ```
 
    判断字符是否是从左到右书写的文字。
 
    ```js
-   var isRTL = I18n.Unicode.isRTL("مرحبًا"); // isRTL = true，阿拉伯语的文字是从左到右书写的文字
+   let isRTL = I18n.Unicode.isRTL("مرحبًا"); // isRTL = true，阿拉伯语的文字是从左到右书写的文字
    isRTL = I18n.Unicode.isRTL("a"); // isRTL = false
    ```
 
    判断字符是否是表意文字。
 
    ```js
-   var isIdeograph = I18n.Unicode.isIdeograph("你好"); // isIdeograph = true
+   let isIdeograph = I18n.Unicode.isIdeograph("你好"); // isIdeograph = true
    isIdeograph = I18n.Unicode.isIdeograph("a"); // isIdeograph = false
    ```
 
    判断字符是否是字母。
 
    ```js
-   var isLetter = I18n.Unicode.isLetter("a"); // isLetter = true
+   let isLetter = I18n.Unicode.isLetter("a"); // isLetter = true
    isLetter = I18n.Unicode.isLetter("."); // isLetter = false
    ```
 
    判断字符是否是小写字母。
 
    ```js
-   var isLowerCase = I18n.Unicode.isLowerCase("a"); // isLetter = true
+   let isLowerCase = I18n.Unicode.isLowerCase("a"); // isLetter = true
    isLowerCase = I18n.Unicode.isLowerCase("A"); // isLetter = false
    ```
 
    判断字符是否是大写字母。
 
    ```js
-   var isUpperCase = I18n.Unicode.isUpperCase("a"); // isUpperCase = false
+   let isUpperCase = I18n.Unicode.isUpperCase("a"); // isUpperCase = false
    isUpperCase = I18n.Unicode.isUpperCase("A"); // isUpperCase = true
    ```
 
@@ -707,7 +703,7 @@ try {
    调用getType接口获取字符的类型。
 
    ```js
-   var type = I18n.Unicode.getType("a"); // type = U_LOWER_CASE_LETTER
+   let type = I18n.Unicode.getType("a"); // type = U_LOWER_CASE_LETTER
    ```
 
 ## 获取日期中年月日的排列顺序
@@ -732,5 +728,5 @@ try {
    接口返回一个字符串，由"y"，"L"，"d"三部分组成，分别表示年、月、日，使用中划线进行拼接。例如，"y-L-d"。
 
    ```js
-   var order = I18n.I18NUtil.getDateOrder("zh-CN"); // order = "y-L-d"，表示中文中年月日的顺序为年-月-日。
+   let order = I18n.I18NUtil.getDateOrder("zh-CN"); // order = "y-L-d"，表示中文中年月日的顺序为年-月-日。
    ```
\ No newline at end of file
diff --git a/zh-cn/application-dev/internationalization/intl-guidelines.md b/zh-cn/application-dev/internationalization/intl-guidelines.md
index 68b7299740326df79e675fa8ca9bd7b7f59e20db..172d24522a9c4724aa6c50680baab9e421cd9dd3 100644
--- a/zh-cn/application-dev/internationalization/intl-guidelines.md
+++ b/zh-cn/application-dev/internationalization/intl-guidelines.md
@@ -48,9 +48,9 @@
 
    
    ```js
-   var locale = "zh-CN";
-   var options = {caseFirst: "false", calendar: "chinese", collation: "pinyin"};
-   var localeObj = new Intl.Locale(locale, options);
+   let locale = "zh-CN";
+   let options = {caseFirst: "false", calendar: "chinese", collation: "pinyin"};
+   let localeObj = new Intl.Locale(locale, options);
    ```
 
 3. 获取Locale的字符串表示。
@@ -58,7 +58,7 @@
      调用toString方法来获取Locale对象的字符串表示，其中包括了语言、区域及其他选项信息。
      
    ```js
-   var localeStr = localeObj.toString(); // localeStr = "zh-CN-u-ca-chinese-co-pinyin-kf-false
+   let localeStr = localeObj.toString(); // localeStr = "zh-CN-u-ca-chinese-co-pinyin-kf-false
    ```
 
 4. 最大化区域信息。
@@ -66,8 +66,8 @@
      调用maximize方法来最大化区域信息，即当缺少脚本与地区信息时，对其进行补全。
      
    ```js
-   var maximizedLocale = localeObj.maximize();
-   var maximizedLocaleStr = maximizedLocale.toString(); // localeStr = "zh-Hans-CN-u-ca-chinese-co-pinyin-kf-false
+   let maximizedLocale = localeObj.maximize();
+   let maximizedLocaleStr = maximizedLocale.toString(); // localeStr = "zh-Hans-CN-u-ca-chinese-co-pinyin-kf-false
    ```
 
 5. 最小化区域信息。
@@ -75,8 +75,8 @@
      调用minimize方法来最小化区域信息，即当存在脚本与地区信息时，对其进行删除。
      
    ```js
-   var minimizedLocale = localeObj.minimize();
-   var minimizedLocaleStr = minimizedLocale.toString(); // zh-u-ca-chinese-co-pinyin-kf-false
+   let minimizedLocale = localeObj.minimize();
+   let minimizedLocaleStr = minimizedLocale.toString(); // zh-u-ca-chinese-co-pinyin-kf-false
    ```
 
 ## 格式化日期时间
@@ -108,14 +108,14 @@
    一种方法是使用DateTimeFormat提供的默认构造函数，通过访问系统语言和地区设置，获取系统默认Locale，并将其作为DateTimeFormat对象内部的Locale。
 
    ```js
-   var dateTimeFormat = new Intl.DateTimeFormat();
+   let dateTimeFormat = new Intl.DateTimeFormat();
    ```
 
      另一种方法是使用开发者提供的Locale和格式化参数来创建日期时间格式化对象。其中，格式化参数是可选的，完整的格式化参数列表见[DateTimeOptions](../reference/apis/js-apis-intl.md#datetimeoptions)。
    
    ```js
-   var options = {dateStyle: "full", timeStyle: "full"};
-   var dateTimeFormat = new Intl.DateTimeFormat("zh-CN", options);
+   let options = {dateStyle: "full", timeStyle: "full"};
+   let dateTimeFormat = new Intl.DateTimeFormat("zh-CN", options);
    ```
 
 3. 格式化日期时间。
@@ -123,10 +123,10 @@
      使用DateTimeFormat的format方法对一个Date对象进行格式化，该方法会返回一个字符串作为格式化的结果。
      
    ```js
-   var options = {dateStyle: "full", timeStyle: "full"};
-   var dateTimeFormat = new Intl.DateTimeFormat("zh-CN", options);
-   var date = new Date(2022, 12, 12, 12, 12, 12);
-   var formatResult = dateTimeFormat.format(date); // formatResult = "2023年1月12日星期四 中国标准时间 下午12:12:12"
+   let options = {dateStyle: "full", timeStyle: "full"};
+   let dateTimeFormat = new Intl.DateTimeFormat("zh-CN", options);
+   let date = new Date(2022, 12, 12, 12, 12, 12);
+   let formatResult = dateTimeFormat.format(date); // formatResult = "2023年1月12日星期四 中国标准时间 下午12:12:12"
    ```
 
 4. 格式化时间段。
@@ -134,10 +134,10 @@
      使用DateTimeFormat的formatRange方法对一个时间段进行格式化。该方法需要传入两个Date对象，分别表示时间段的起止日期，返回一个字符串作为格式化的结果。
      
    ```js
-   var startDate = new Date(2021, 11, 17, 3, 24, 0);
-   var endDate = new Date(2021, 11, 18, 3, 24, 0);
-   var datefmt = new Intl.DateTimeFormat("en-GB");
-   var formatRangeResult = datefmt.formatRange(startDate, endDate); // formatRangeResult = "17/12/2021-18/12/2021"
+   let startDate = new Date(2021, 11, 17, 3, 24, 0);
+   let endDate = new Date(2021, 11, 18, 3, 24, 0);
+   let datefmt = new Intl.DateTimeFormat("en-GB");
+   let formatRangeResult = datefmt.formatRange(startDate, endDate); // formatRangeResult = "17/12/2021-18/12/2021"
    ```
 
 5. 访问日期时间格式化对象的相关属性。
@@ -145,9 +145,9 @@
      DateTimeFormat的resolvedOptions方法会返回一个对象，该对象包含了DateTimeFormat对象的所有相关属性及其值。
      
    ```js
-   var options = {dateStyle: "full", timeStyle: "full"};
-   var dateTimeFormat = new Intl.DateTimeFormat("zh-CN", options);
-   var resolvedOptions = dateTimeFormat.resolvedOptions(); // resolvedOptions = {"locale": "zh-CN", "calendar": "gregorian", "dateStyle":"full", "timeStyle":"full", "timeZone": "CST"}
+   let options = {dateStyle: "full", timeStyle: "full"};
+   let dateTimeFormat = new Intl.DateTimeFormat("zh-CN", options);
+   let resolvedOptions = dateTimeFormat.resolvedOptions(); // resolvedOptions = {"locale": "zh-CN", "calendar": "gregorian", "dateStyle":"full", "timeStyle":"full", "timeZone": "CST"}
    ```
 
 ## 数字格式化
@@ -178,14 +178,14 @@
    一种方法是使用NumberFormat提供的默认构造函数，通过访问系统的语言和地区以获取系统默认Locale并进行设置（intl为导入的模块名）。
 
    ```js
-   var numberFormat = new Intl.NumberFormat();
+   let numberFormat = new Intl.NumberFormat();
    ```
 
      另一种方法是使用开发者提供的Locale和格式化参数来创建数字格式化对象。其中，格式化参数是可选的，完整的格式化参数列表参见[NumberOptions](../reference/apis/js-apis-intl.md#numberoptions)。
    
    ```js
-   var options = {compactDisplay: "short", notation: "compact"};
-   var numberFormat = new Intl.NumberFormat("zh-CN", options);
+   let options = {compactDisplay: "short", notation: "compact"};
+   let numberFormat = new Intl.NumberFormat("zh-CN", options);
    ```
 
 3. 数字格式化。
@@ -193,10 +193,10 @@
      使用NumberFormat的format方法对传入的数字进行格式化。该方法返回一个字符串作为格式化的结果。
      
    ```js
-   var options = {compactDisplay: "short", notation: "compact"};
-   var numberFormat = new Intl.NumberFormat("zh-CN", options);
-   var number = 1234.5678
-   var formatResult = numberFormat.format(number); // formatResult = "1235"
+   let options = {compactDisplay: "short", notation: "compact"};
+   let numberFormat = new Intl.NumberFormat("zh-CN", options);
+   let number = 1234.5678
+   let formatResult = numberFormat.format(number); // formatResult = "1235"
    ```
 
 4. 访问数字格式化对象的相关属性。
@@ -204,9 +204,9 @@
      NumberFormat的resolvedOptions方法会返回一个对象，该对象包含了NumberFormat对象的所有相关属性及其值。
      
    ```js
-   var options = {compactDisplay: "short", notation: "compact"};
-   var numberFormat = new Intl.NumberFormat("zh-CN", options);
-   var resolvedOptions = numberFormat.resolvedOptions();  // resolvedOptions = {"locale": "zh-CN", "compactDisplay": "short", "notation": "compact", "numberingSystem": "Latn"}
+   let options = {compactDisplay: "short", notation: "compact"};
+   let numberFormat = new Intl.NumberFormat("zh-CN", options);
+   let resolvedOptions = numberFormat.resolvedOptions();  // resolvedOptions = {"locale": "zh-CN", "compactDisplay": "short", "notation": "compact", "numberingSystem": "Latn"}
    ```
 
 ## 字符串排序
@@ -237,14 +237,14 @@
    一种方法是使用Collator提供的默认构造函数，通过访问系统的语言和地区以获取系统默认Locale并进行设置（intl为导入的模块名）。
 
    ```js
-   var collator = new Intl.Collator();
+   let collator = new Intl.Collator();
    ```
 
      另一种方法是使用开发者提供的Locale和其他相关参数来创建Collator对象，完整的参数列表参见[CollatorOptions](../reference/apis/js-apis-intl.md#collatoroptions9)。
      其中，sensitivity参数用于控制哪些级别的差异会被用于比较两个字符串。取值"base"表示，仅比较字符本身，不考虑重音符号、大小写差异。例如，'a' != 'b'，'a' == 'á'，'a' == 'A'。取值"accent"表示考虑重音符号，不考虑大小写的差异。例如，'a' != 'b'，'a' != 'á'，'a' == 'A'。取值"case"表示考虑大小写的差异，不考虑重音符号的差异。例如，'a' != 'b'，'a' == 'á'，'a' != 'A'。取值"variant"表示考虑重音符号、大小写等方面差异。例如'a' != 'b'，'a' != 'á'，'a' != 'A'。
    
    ```js
-   var collator= new Intl.Collator("zh-CN", {localeMatcher: "best fit", usage: "sort", sensitivity: "case"});
+   let collator= new Intl.Collator("zh-CN", {localeMatcher: "best fit", usage: "sort", sensitivity: "case"});
    ```
 
 3. 比较字符串。
@@ -252,10 +252,10 @@
      使用Collator的compare方法对传入的两个字符串进行比较。该方法返回一个数值作为比较的结果，返回-1表示第一个字符串小于第二个字符串，返回1表示第一个字符大于第二个字符串，返回0表示两个字符串相同。基于两个字符串的比较结果，开发者可以字符串集合进行排序。
      
    ```js
-   var collator= new Intl.Collator("zh-CN", {localeMatcher: "best fit", usage: "sort", sensitivity: "case"});
-   var str1 = "first string";
-   var str2 = "second string";
-   var compareResult = collator.compare(str1, str2); // compareResult = -1
+   let collator= new Intl.Collator("zh-CN", {localeMatcher: "best fit", usage: "sort", sensitivity: "case"});
+   let str1 = "first string";
+   let str2 = "second string";
+   let compareResult = collator.compare(str1, str2); // compareResult = -1
    str1 = "first";
    str2 = "First";
    compareResult = collator.compare(str1, str2); // compareResult = -1
@@ -266,8 +266,8 @@
      Collator的resolvedOptions方法会返回一个对象，该对象包含了Collator对象的所有相关属性及其值。
      
    ```js
-   var collator= new Intl.Collator("zh-CN", {localeMatcher: "best fit", usage: "sort"});
-   var options = collator.resolvedOptions(); // options = {"localeMatcher": "best fit", "locale": "zh-CN", "usage": "sort", "sensitivity": "variant", "ignorePunctuation": "false", "numeric": false, "caseFirst": "false", "collation": "default"}
+   let collator= new Intl.Collator("zh-CN", {localeMatcher: "best fit", usage: "sort"});
+   let options = collator.resolvedOptions(); // options = {"localeMatcher": "best fit", "locale": "zh-CN", "usage": "sort", "sensitivity": "variant", "ignorePunctuation": "false", "numeric": false, "caseFirst": "false", "collation": "default"}
    ```
 
 ## 判定单复数类别
@@ -298,13 +298,13 @@
    一种方法是使用PluralRules提供的默认构造函数，通过访问系统的语言和地区以获取系统默认Locale并进行设置（intl为导入的模块名）。
 
    ```js
-   var pluralRules = new Intl.PluralRules();
+   let pluralRules = new Intl.PluralRules();
    ```
 
      另一种方法是使用开发者提供的Locale和其他相关参数来创建单复数对象。完整的参数列表参见[PluralRulesOptions](../reference/apis/js-apis-intl.md#pluralrulesoptions9)。
    
    ```js
-   var pluralRules = new Intl.PluralRules("zh-CN", {localeMatcher: "best fit", type: "cardinal"});
+   let pluralRules = new Intl.PluralRules("zh-CN", {localeMatcher: "best fit", type: "cardinal"});
    ```
 
 3. 计算数字单复数类别。
@@ -312,9 +312,9 @@
      使用PluralRules的select方法计算传入数字的单复数类别。该方法返回一个字符串作为传入数字的类别，包括："zero", "one", "two", "few", "many", "other"六个类别。
      
    ```js
-   var pluralRules = new Intl.PluralRules("zh-CN", {localeMatcher: "best fit", type: "cardinal"});
-   var number = 1234.5678
-   var categoryResult = pluralRules.select(number); // categoryResult = "other"
+   let pluralRules = new Intl.PluralRules("zh-CN", {localeMatcher: "best fit", type: "cardinal"});
+   let number = 1234.5678
+   let categoryResult = pluralRules.select(number); // categoryResult = "other"
    ```
 
 ## 相对时间格式化
@@ -346,13 +346,13 @@
    一种方法是使用RelativeTimeFormat提供的默认构造函数，通过访问系统的语言和地区以获取系统默认Locale并进行设置（intl为导入的模块名）。
    
    ```js
-   var relativeTimeFormat = new Intl.RelativeTimeFormat();
+   let relativeTimeFormat = new Intl.RelativeTimeFormat();
    ```
 
      另一种方法是使用开发者提供的Locale和格式化参数来创建相对时间格式化对象。其中，格式化参数是可选的，完整的参数列表参见[ RelativeTimeFormatInputOptions](../reference/apis/js-apis-intl.md#relativetimeformatinputoptions9)。
    
    ```js
-   var relativeTimeFormat = new Intl.RelativeTimeFormat("zh-CN", {numeric: "always", style: "long"});
+   let relativeTimeFormat = new Intl.RelativeTimeFormat("zh-CN", {numeric: "always", style: "long"});
    ```
 
 3. 相对时间格式化。
@@ -360,10 +360,10 @@
      使用RelativeTimeFormat的format方法对相对时间进行格式化。方法接收一个表示相对时间长度的数值和表示单位的字符串，其中单位包括："year", "quarter", "month", "week", "day", "hour", "minute", "second"。方法返回一个字符串作为格式化的结果。
      
    ```js
-   var relativeTimeFormat = new Intl.RelativeTimeFormat("zh-CN", {numeric: "always", style: "long"});
-   var number = 2;
-   var unit = "year"
-   var formatResult = relativeTimeFormat.format(number, unit); // 2年后
+   let relativeTimeFormat = new Intl.RelativeTimeFormat("zh-CN", {numeric: "always", style: "long"});
+   let number = 2;
+   let unit = "year"
+   let formatResult = relativeTimeFormat.format(number, unit); // 2年后
    ```
 
 4. 获取相对时间格式化结果的各个部分。
@@ -371,10 +371,10 @@
      获取相对时间格式化结果的各个部分，从而自定义格式化结果。
      
    ```js
-   var relativeTimeFormat = new Intl.RelativeTimeFormat("zh-CN", {numeric: "always", style: "long"});
-   var number = 2;
-   var unit = "year"
-   var formatPartsResult = relativeTimeFormat.formatToParts(number, unit); // formatPartsResult = [{"type": "integer", "value": "2", "unit": "year"}, {"type":"literal", "value": "年后"}]
+   let relativeTimeFormat = new Intl.RelativeTimeFormat("zh-CN", {numeric: "always", style: "long"});
+   let number = 2;
+   let unit = "year"
+   let formatPartsResult = relativeTimeFormat.formatToParts(number, unit); // formatPartsResult = [{"type": "integer", "value": "2", "unit": "year"}, {"type":"literal", "value": "年后"}]
    ```
 
 5. 访问相对时间格式化对象的相关属性。
@@ -382,8 +382,8 @@
      RelativeTimeFormat的resolvedOptions方法会返回一个对象，该对象包含了RelativeTimeFormat对象的所有相关属性及其值，完整的属性列表参见[ RelativeTimeFormatResolvedOptions](../reference/apis/js-apis-intl.md#relativetimeformatresolvedoptions8)。
      
    ```js
-   var relativeTimeFormat = new Intl.RelativeTimeFormat("zh-CN", {numeric: "always", style: "long"});
-   var options = relativeTimeFormat.resolvedOptions(); // options = {"locale": "zh-CN", "style": "long", "numeric": "always", "numberingSystem": "latn"}
+   let relativeTimeFormat = new Intl.RelativeTimeFormat("zh-CN", {numeric: "always", style: "long"});
+   let options = relativeTimeFormat.resolvedOptions(); // options = {"locale": "zh-CN", "style": "long", "numeric": "always", "numberingSystem": "latn"}
    ```
 
 ## 相关实例
diff --git a/zh-cn/application-dev/reference/apis/js-apis-i18n.md b/zh-cn/application-dev/reference/apis/js-apis-i18n.md
index 7f4806e2cd02c761d139bb4e1368d40d0b9ff604..fb0fdee505e8c217d264088978a0d646be1634c7 100644
--- a/zh-cn/application-dev/reference/apis/js-apis-i18n.md
+++ b/zh-cn/application-dev/reference/apis/js-apis-i18n.md
@@ -51,7 +51,7 @@ static getDisplayCountry(country: string, locale: string, sentenceCase?: boolean
 **示例：** 
   ```js
   try {
-    var displayCountry = I18n.System.getDisplayCountry("zh-CN", "en-GB"); // displayCountry = "China"
+    let displayCountry = I18n.System.getDisplayCountry("zh-CN", "en-GB"); // displayCountry = "China"
   } catch(error) {
     console.error(`call System.getDisplayCountry failed, error code: ${error.code}, message: ${error.message}.`)
   }
@@ -90,7 +90,7 @@ static getDisplayLanguage(language: string, locale: string, sentenceCase?: boole
 **示例：** 
   ```js
   try {
-    var displayLanguage = I18n.System.getDisplayLanguage("zh", "en-GB"); // displayLanguage = Chinese
+    let displayLanguage = I18n.System.getDisplayLanguage("zh", "en-GB"); // displayLanguage = Chinese
   } catch(error) {
     console.error(`call System.getDisplayLanguage failed, error code: ${error.code}, message: ${error.message}.`)
   }
@@ -121,7 +121,7 @@ static getSystemLanguages(): Array<string>
 **示例：** 
   ```js
   try {
-    var systemLanguages = I18n.System.getSystemLanguages(); // [ "en-Latn-US", "zh-Hans" ]
+    let systemLanguages = I18n.System.getSystemLanguages(); // [ "en-Latn-US", "zh-Hans" ]
   } catch(error) {
     console.error(`call System.getSystemLanguages failed, error code: ${error.code}, message: ${error.message}.`)
   }
@@ -158,7 +158,7 @@ static getSystemCountries(language: string): Array<string>
 **示例：** 
   ```js
   try {
-    var systemCountries = I18n.System.getSystemCountries('zh'); // systemCountries = [ "ZW", "YT", "YE", ..., "ER", "CN", "DE" ]，共计240个国家或地区
+    let systemCountries = I18n.System.getSystemCountries('zh'); // systemCountries = [ "ZW", "YT", "YE", ..., "ER", "CN", "DE" ]，共计240个国家或地区
   } catch(error) {
     console.error(`call System.getSystemCountries failed, error code: ${error.code}, message: ${error.message}.`)
   }
@@ -196,7 +196,7 @@ static isSuggested(language: string, region?: string): boolean
 **示例：** 
   ```js
   try {
-    var res = I18n.System.isSuggested('zh', 'CN');  // res = true
+    let res = I18n.System.isSuggested('zh', 'CN');  // res = true
   } catch(error) {
     console.error(`call System.isSuggested failed, error code: ${error.code}, message: ${error.message}.`)
   }
@@ -227,7 +227,7 @@ static getSystemLanguage(): string
 **示例：** 
   ```js
   try {
-    var systemLanguage = I18n.System.getSystemLanguage();  // systemLanguage为当前系统语言
+    let systemLanguage = I18n.System.getSystemLanguage();  // systemLanguage为当前系统语言
   } catch(error) {
     console.error(`call System.getSystemLanguage failed, error code: ${error.code}, message: ${error.message}.`)
   }
@@ -293,7 +293,7 @@ static getSystemRegion(): string
 **示例：** 
   ```js
   try {
-    var systemRegion = I18n.System.getSystemRegion(); // 获取系统当前地区设置
+    let systemRegion = I18n.System.getSystemRegion(); // 获取系统当前地区设置
   } catch(error) {
     console.error(`call System.getSystemRegion failed, error code: ${error.code}, message: ${error.message}.`)
   }
@@ -359,7 +359,7 @@ static getSystemLocale(): string
 **示例：** 
   ```js
   try {
-    var systemLocale = I18n.System.getSystemLocale();  // 获取系统当前Locale
+    let systemLocale = I18n.System.getSystemLocale();  // 获取系统当前Locale
   } catch(error) {
     console.error(`call System.getSystemLocale failed, error code: ${error.code}, message: ${error.message}.`)
   }
@@ -425,7 +425,7 @@ static is24HourClock(): boolean
 **示例：** 
   ```js
   try {
-    var is24HourClock = I18n.System.is24HourClock();  // 系统24小时开关是否开启
+    let is24HourClock = I18n.System.is24HourClock();  // 系统24小时开关是否开启
   } catch(error) {
     console.error(`call System.is24HourClock failed, error code: ${error.code}, message: ${error.message}.`)
   }
@@ -497,8 +497,8 @@ static addPreferredLanguage(language: string, index?: number): void
 **示例：** 
   ```js
   // 将语言zh-CN添加到系统偏好语言列表中
-  var language = 'zh-CN';
-  var index = 0;
+  let language = 'zh-CN';
+  let index = 0;
   try {
     I18n.System.addPreferredLanguage(language, index); // 将zh-CN添加到系统偏好语言列表的第1位
   } catch(error) {
@@ -535,7 +535,7 @@ static removePreferredLanguage(index: number): void
 **示例：** 
   ```js
   // 删除系统偏好语言列表中的第一个偏好语言
-  var index = 0;
+  let index = 0;
   try {
     I18n.System.removePreferredLanguage(index);
   } catch(error) {
@@ -568,7 +568,7 @@ static getPreferredLanguageList(): Array<string>
 **示例：** 
   ```js
   try {
-    var preferredLanguageList = I18n.System.getPreferredLanguageList(); // 获取系统当前偏好语言列表
+    let preferredLanguageList = I18n.System.getPreferredLanguageList(); // 获取系统当前偏好语言列表
   } catch(error) {
     console.error(`call System.getPreferredLanguageList failed, error code: ${error.code}, message: ${error.message}.`)
   }
@@ -599,7 +599,7 @@ static getFirstPreferredLanguage(): string
 **示例：** 
   ```js
   try {
-    var firstPreferredLanguage = I18n.System.getFirstPreferredLanguage();  // 获取系统当前偏好语言列表中的第一个偏好语言
+    let firstPreferredLanguage = I18n.System.getFirstPreferredLanguage();  // 获取系统当前偏好语言列表中的第一个偏好语言
   } catch(error) {
     console.error(`call System.getFirstPreferredLanguage failed, error code: ${error.code}, message: ${error.message}.`)
   }
@@ -630,7 +630,7 @@ static getAppPreferredLanguage(): string
 **示例：** 
   ```js
   try {
-    var appPreferredLanguage = I18n.System.getAppPreferredLanguage(); // 获取应用偏好语言
+    let appPreferredLanguage = I18n.System.getAppPreferredLanguage(); // 获取应用偏好语言
   } catch(error) {
     console.error(`call System.getAppPreferredLanguage failed, error code: ${error.code}, message: ${error.message}.`)
   }
@@ -696,7 +696,7 @@ static getUsingLocalDigit(): boolean
 **示例：** 
   ```ts
   try {
-    var status = I18n.System.getUsingLocalDigit();  // 判断本地化数字开关是否打开
+    let status = I18n.System.getUsingLocalDigit();  // 判断本地化数字开关是否打开
   } catch(error) {
     console.error(`call System.getUsingLocalDigit failed, error code: ${error.code}, message: ${error.message}.`)
   }
@@ -776,8 +776,8 @@ setTime(date: Date): void
 
 **示例：** 
   ```js
-  var calendar = I18n.getCalendar("en-US", "gregory");
-  var date = new Date(2021, 10, 7, 8, 0, 0, 0);
+  let calendar = I18n.getCalendar("en-US", "gregory");
+  let date = new Date(2021, 10, 7, 8, 0, 0, 0);
   calendar.setTime(date);
   ```
 
@@ -798,7 +798,7 @@ setTime(time: number): void
 
 **示例：** 
   ```js
-  var calendar = I18n.getCalendar("en-US", "gregory");
+  let calendar = I18n.getCalendar("en-US", "gregory");
   calendar.setTime(10540800000);
   ```
 
@@ -824,7 +824,7 @@ set(year: number, month: number, date:number, hour?: number, minute?: number, se
 
 **示例：** 
   ```js
-  var calendar = I18n.getCalendar("zh-Hans");
+  let calendar = I18n.getCalendar("zh-Hans");
   calendar.set(2021, 10, 1, 8, 0, 0); // set time to 2021.10.1 08:00:00
   ```
 
@@ -845,7 +845,7 @@ setTimeZone(timezone: string): void
 
 **示例：** 
   ```js
-  var calendar = I18n.getCalendar("zh-Hans");
+  let calendar = I18n.getCalendar("zh-Hans");
   calendar.setTimeZone("Asia/Shanghai");
   ```
 
@@ -866,9 +866,9 @@ getTimeZone(): string
 
 **示例：** 
   ```js
-  var calendar = I18n.getCalendar("zh-Hans");
+  let calendar = I18n.getCalendar("zh-Hans");
   calendar.setTimeZone("Asia/Shanghai");
-  var timezone = calendar.getTimeZone(); // timezone = "Asia/Shanghai"
+  let timezone = calendar.getTimeZone(); // timezone = "Asia/Shanghai"
   ```
 
 
@@ -888,8 +888,8 @@ getFirstDayOfWeek(): number
 
 **示例：** 
   ```js
-  var calendar = I18n.getCalendar("en-US", "gregory");
-  var firstDayOfWeek = calendar.getFirstDayOfWeek(); // firstDayOfWeek = 1
+  let calendar = I18n.getCalendar("en-US", "gregory");
+  let firstDayOfWeek = calendar.getFirstDayOfWeek(); // firstDayOfWeek = 1
   ```
 
 
@@ -909,9 +909,9 @@ setFirstDayOfWeek(value: number): void
 
 **示例：** 
   ```js
-  var calendar = I18n.getCalendar("zh-Hans");
+  let calendar = I18n.getCalendar("zh-Hans");
   calendar.setFirstDayOfWeek(3);
-  var firstDayOfWeek = calendar.getFirstDayOfWeek(); // firstDayOfWeek = 3
+  let firstDayOfWeek = calendar.getFirstDayOfWeek(); // firstDayOfWeek = 3
   ```
 
 
@@ -931,8 +931,8 @@ getMinimalDaysInFirstWeek(): number
 
 **示例：** 
   ```js
-  var calendar = I18n.getCalendar("zh-Hans");
-  var minimalDaysInFirstWeek = calendar.getMinimalDaysInFirstWeek(); // minimalDaysInFirstWeek = 1
+  let calendar = I18n.getCalendar("zh-Hans");
+  let minimalDaysInFirstWeek = calendar.getMinimalDaysInFirstWeek(); // minimalDaysInFirstWeek = 1
   ```
 
 
@@ -952,9 +952,9 @@ setMinimalDaysInFirstWeek(value: number): void
 
 **示例：** 
   ```js
-  var calendar = I18n.getCalendar("zh-Hans");
+  let calendar = I18n.getCalendar("zh-Hans");
   calendar.setMinimalDaysInFirstWeek(3);
-  var minimalDaysInFirstWeek = calendar.getMinimalDaysInFirstWeek(); // minimalDaysInFirstWeek = 3
+  let minimalDaysInFirstWeek = calendar.getMinimalDaysInFirstWeek(); // minimalDaysInFirstWeek = 3
   ```
 
 
@@ -980,9 +980,9 @@ get(field: string): number
 
 **示例：** 
   ```js
-  var calendar = I18n.getCalendar("zh-Hans");
+  let calendar = I18n.getCalendar("zh-Hans");
   calendar.set(2021, 10, 1, 8, 0, 0); // set time to 2021.10.1 08:00:00
-  hourOfDay = calendar.get("hour_of_day"); // hourOfDay = 8
+  let hourOfDay = calendar.get("hour_of_day"); // hourOfDay = 8
   ```
 
 
@@ -1008,8 +1008,8 @@ getDisplayName(locale: string): string
 
 **示例：** 
   ```js
-  var calendar = I18n.getCalendar("en-US", "buddhist");
-  var calendarName = calendar.getDisplayName("zh"); // calendarName = "佛历"
+  let calendar = I18n.getCalendar("en-US", "buddhist");
+  let calendarName = calendar.getDisplayName("zh"); // calendarName = "佛历"
   ```
 
 
@@ -1035,10 +1035,10 @@ isWeekend(date?: Date): boolean
 
 **示例：** 
   ```js
-  var calendar = I18n.getCalendar("zh-Hans");
+  let calendar = I18n.getCalendar("zh-Hans");
   calendar.set(2021, 11, 11, 8, 0, 0); // set time to 2021.11.11 08:00:00
   calendar.isWeekend(); // false
-  var date = new Date(2011, 11, 6, 9, 0, 0);
+  let date = new Date(2011, 11, 6, 9, 0, 0);
   calendar.isWeekend(date); // true
   ```
 
@@ -1063,7 +1063,7 @@ constructor(country: string, options?: PhoneNumberFormatOptions)
 
 **示例：** 
   ```js
-  var phoneNumberFormat= new I18n.PhoneNumberFormat("CN", {"type": "E164"});
+  let phoneNumberFormat= new I18n.PhoneNumberFormat("CN", {"type": "E164"});
   ```
 
 
@@ -1089,8 +1089,8 @@ isValidNumber(number: string): boolean
 
 **示例：** 
   ```js
-  var phonenumberfmt = new I18n.PhoneNumberFormat("CN");
-  var isValidNumber = phonenumberfmt.isValidNumber("15812312312"); // isValidNumber = true
+  let phonenumberfmt = new I18n.PhoneNumberFormat("CN");
+  let isValidNumber = phonenumberfmt.isValidNumber("15812312312"); // isValidNumber = true
   ```
 
 
@@ -1116,8 +1116,8 @@ format(number: string): string
 
 **示例：** 
   ```js
-  var phonenumberfmt = new I18n.PhoneNumberFormat("CN");
-  var formattedPhoneNumber = phonenumberfmt.format("15812312312"); // formattedPhoneNumber = "158 1231 2312"
+  let phonenumberfmt = new I18n.PhoneNumberFormat("CN");
+  let formattedPhoneNumber = phonenumberfmt.format("15812312312"); // formattedPhoneNumber = "158 1231 2312"
   ```
 
 
@@ -1144,8 +1144,8 @@ getLocationName(number: string, locale: string): string
 
 **示例：** 
   ```js
-  var phonenumberfmt = new I18n.PhoneNumberFormat("CN");
-  var locationName = phonenumberfmt.getLocationName("15812312345", "zh-CN"); // locationName = "广东省湛江市"
+  let phonenumberfmt = new I18n.PhoneNumberFormat("CN");
+  let locationName = phonenumberfmt.getLocationName("15812312345", "zh-CN"); // locationName = "广东省湛江市"
   ```
 
 
@@ -1194,7 +1194,7 @@ getInstance(locale?:string): IndexUtil
 
 **示例：** 
   ```js
-  var indexUtil= I18n.getInstance("zh-CN");
+  let indexUtil= I18n.getInstance("zh-CN");
   ```
 
 
@@ -1217,10 +1217,10 @@ getIndexList(): Array<string>
 
 **示例：** 
   ```js
-  var indexUtil = I18n.getInstance("zh-CN");
+  let indexUtil = I18n.getInstance("zh-CN");
   // indexList = [ "...", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N",
   //              "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z", "..." ]
-  var indexList = indexUtil.getIndexList();
+  let indexList = indexUtil.getIndexList();
   ```
 
 
@@ -1240,7 +1240,7 @@ addLocale(locale: string): void
 
 **示例：** 
   ```js
-  var indexUtil = I18n.getInstance("zh-CN");
+  let indexUtil = I18n.getInstance("zh-CN");
   indexUtil.addLocale("en-US");
   ```
 
@@ -1267,8 +1267,8 @@ getIndex(text: string): string
 
 **示例：** 
   ```js
-  var indexUtil= I18n.getInstance("zh-CN");
-  var index = indexUtil.getIndex("hi");  // index = "H"
+  let indexUtil= I18n.getInstance("zh-CN");
+  let index = indexUtil.getIndex("hi");  // index = "H"
   ```
 
 
@@ -1294,7 +1294,7 @@ getLineInstance(locale: string): BreakIterator
 
 **示例：** 
   ```js
-  var iterator = I18n.getLineInstance("en");
+  let iterator = I18n.getLineInstance("en");
   ```
 
 
@@ -1317,7 +1317,7 @@ setLineBreakText(text: string): void
 
 **示例：** 
   ```js
-  var iterator = I18n.getLineInstance("en");
+  let iterator = I18n.getLineInstance("en");
   iterator.setLineBreakText("Apple is my favorite fruit."); // 设置短句文本
   ```
 
@@ -1338,9 +1338,9 @@ getLineBreakText(): string
 
 **示例：** 
   ```js
-  var iterator = I18n.getLineInstance("en");
+  let iterator = I18n.getLineInstance("en");
   iterator.setLineBreakText("Apple is my favorite fruit.");
-  var breakText = iterator.getLineBreakText(); // breakText = "Apple is my favorite fruit."
+  let breakText = iterator.getLineBreakText(); // breakText = "Apple is my favorite fruit."
   ```
 
 
@@ -1360,9 +1360,9 @@ current(): number
 
 **示例：** 
   ```js
-  var iterator = I18n.getLineInstance("en");
+  let iterator = I18n.getLineInstance("en");
   iterator.setLineBreakText("Apple is my favorite fruit.");
-  var currentPos = iterator.current(); // currentPos = 0
+  let currentPos = iterator.current(); // currentPos = 0
   ```
 
 
@@ -1382,9 +1382,9 @@ first(): number
 
 **示例：** 
   ```js
-  var iterator = i18n.getLineInstance("en");
+  let iterator = i18n.getLineInstance("en");
   iterator.setLineBreakText("Apple is my favorite fruit.");
-  var firstPos = iterator.first(); // firstPos = 0
+  let firstPos = iterator.first(); // firstPos = 0
   ```
 
 
@@ -1404,9 +1404,9 @@ last(): number
 
 **示例：** 
   ```js
-  var iterator = I18n.getLineInstance("en");
+  let iterator = I18n.getLineInstance("en");
   iterator.setLineBreakText("Apple is my favorite fruit.");
-  var lastPos = iterator.last(); // lastPos = 27
+  let lastPos = iterator.last(); // lastPos = 27
   ```
 
 
@@ -1432,9 +1432,9 @@ next(index?: number): number
 
 **示例：** 
   ```js
-  var iterator = I18n.getLineInstance("en");
+  let iterator = I18n.getLineInstance("en");
   iterator.setLineBreakText("Apple is my favorite fruit.");
-  var pos = iterator.first(); // pos = 0
+  let pos = iterator.first(); // pos = 0
   pos = iterator.next(); // pos = 6
   pos = iterator.next(10); // pos = -1
   ```
@@ -1456,9 +1456,9 @@ previous(): number
 
 **示例：** 
   ```js
-  var iterator = I18n.getLineInstance("en");
+  let iterator = I18n.getLineInstance("en");
   iterator.setLineBreakText("Apple is my favorite fruit.");
-  var pos = iterator.first(); // pos = 0
+  let pos = iterator.first(); // pos = 0
   pos = iterator.next(3); // pos = 12
   pos = iterator.previous(); // pos = 9
   ```
@@ -1486,9 +1486,9 @@ following(offset: number): number
 
 **示例：** 
   ```js
-  var iterator = I18n.getLineInstance("en");
+  let iterator = I18n.getLineInstance("en");
   iterator.setLineBreakText("Apple is my favorite fruit.");
-  var pos = iterator.following(0); // pos = 6
+  let pos = iterator.following(0); // pos = 6
   pos = iterator.following(100); // pos = -1
   pos = iterator.current(); // pos = 27
   ```
@@ -1516,9 +1516,9 @@ isBoundary(offset: number): boolean
 
 **示例：** 
   ```js
-  var iterator = I18n.getLineInstance("en");
+  let iterator = I18n.getLineInstance("en");
   iterator.setLineBreakText("Apple is my favorite fruit.");
-  var isBoundary = iterator.isBoundary(0); // isBoundary = true;
+  let isBoundary = iterator.isBoundary(0); // isBoundary = true;
   isBoundary = iterator.isBoundary(5); // isBoundary = false;
   ```
 
@@ -1545,7 +1545,7 @@ getTimeZone(zoneID?: string): TimeZone
 
 **示例：** 
   ```js
-  var timezone = I18n.getTimeZone();
+  let timezone = I18n.getTimeZone();
   ```
 
 
@@ -1568,8 +1568,8 @@ getID(): string
 
 **示例：** 
   ```js
-  var timezone = I18n.getTimeZone();
-  var timezoneID = timezone.getID(); // timezoneID = "Asia/Shanghai"
+  let timezone = I18n.getTimeZone();
+  let timezoneID = timezone.getID(); // timezoneID = "Asia/Shanghai"
   ```
 
 
@@ -1596,8 +1596,8 @@ getDisplayName(locale?: string, isDST?: boolean): string
 
 **示例：** 
   ```js
-  var timezone = I18n.getTimeZone();
-  var timezoneName = timezone.getDisplayName("zh-CN", false); // timezoneName = "中国标准时间"
+  let timezone = I18n.getTimeZone();
+  let timezoneName = timezone.getDisplayName("zh-CN", false); // timezoneName = "中国标准时间"
   ```
 
 
@@ -1617,8 +1617,8 @@ getRawOffset(): number
 
 **示例：** 
   ```js
-  var timezone = I18n.getTimeZone();
-  var offset = timezone.getRawOffset(); // offset = 28800000
+  let timezone = I18n.getTimeZone();
+  let offset = timezone.getRawOffset(); // offset = 28800000
   ```
 
 
@@ -1638,8 +1638,8 @@ getOffset(date?: number): number
 
 **示例：** 
   ```js
-  var timezone = I18n.getTimeZone();
-  var offset = timezone.getOffset(1234567890); // offset = 28800000
+  let timezone = I18n.getTimeZone();
+  let offset = timezone.getOffset(1234567890); // offset = 28800000
   ```
 
 
@@ -1660,7 +1660,7 @@ static getAvailableIDs(): Array<string>
 **示例：** 
   ```ts
   // ids = ["America/Adak", "America/Anchorage", "America/Bogota", "America/Denver", "America/Los_Angeles", "America/Montevideo", "America/Santiago", "America/Sao_Paulo", "Asia/Ashgabat", "Asia/Hovd", "Asia/Jerusalem", "Asia/Magadan", "Asia/Omsk", "Asia/Shanghai", "Asia/Tokyo", "Asia/Yerevan", "Atlantic/Cape_Verde", "Australia/Lord_Howe", "Europe/Dublin", "Europe/London", "Europe/Moscow", "Pacific/Auckland", "Pacific/Easter", "Pacific/Pago-Pago"], 当前共支持24个时区
-  var ids = I18n.TimeZone.getAvailableIDs();
+  let ids = I18n.TimeZone.getAvailableIDs();
   ```
 
 
@@ -1681,7 +1681,7 @@ static getAvailableZoneCityIDs(): Array<string>
 **示例：** 
   ```ts
   // cityIDs = ["Auckland", "Magadan", "Lord Howe Island", "Tokyo", "Shanghai", "Hovd", "Omsk", "Ashgabat", "Yerevan", "Moscow", "Tel Aviv", "Dublin", "London", "Praia", "Montevideo", "Brasília", "Santiago", "Bogotá", "Easter Island", "Salt Lake City", "Los Angeles", "Anchorage", "Adak", "Pago Pago"]，当前共支持24个时区城市
-  var cityIDs = I18n.TimeZone.getAvailableZoneCityIDs();
+  let cityIDs = I18n.TimeZone.getAvailableZoneCityIDs();
   ```
 
 
@@ -1708,7 +1708,7 @@ static getCityDisplayName(cityID: string, locale: string): string
 
 **示例：** 
   ```ts
-  var displayName = I18n.TimeZone.getCityDisplayName("Shanghai", "zh-CN"); // displayName = "上海(中国)"
+  let displayName = I18n.TimeZone.getCityDisplayName("Shanghai", "zh-CN"); // displayName = "上海(中国)"
   ```
 
 
@@ -1734,7 +1734,7 @@ static getTimezoneFromCity(cityID: string): TimeZone
 
 **示例：** 
   ```ts
-  var timezone = I18n.TimeZone.getTimezoneFromCity("Shanghai");
+  let timezone = I18n.TimeZone.getTimezoneFromCity("Shanghai");
   ```
 
 
@@ -1759,7 +1759,7 @@ static getAvailableIDs(): string[]
   ```ts
   // ids = ["ASCII-Latin", "Accents-Any", "Amharic-Latin/BGN", ...]，共支持671个id
   // 每一个id由使用中划线分割的两部分组成，格式为 source-destination
-  var ids = I18n.Transliterator.getAvailableIDs();
+  let ids = I18n.Transliterator.getAvailableIDs();
   ```
 
 
@@ -1785,7 +1785,7 @@ static getInstance(id: string): Transliterator
 
 **示例：** 
   ```ts
-  var transliterator = I18n.Transliterator.getInstance("Any-Latn");
+  let transliterator = I18n.Transliterator.getInstance("Any-Latn");
   ```
 
 
@@ -1811,8 +1811,8 @@ transform(text: string): string
 
 **示例：** 
   ```ts
-  var transliterator = I18n.Transliterator.getInstance("Any-Latn");
-  var res = transliterator.transform("中国"); // res = "zhōng guó"
+  let transliterator = I18n.Transliterator.getInstance("Any-Latn");
+  let res = transliterator.transform("中国"); // res = "zhōng guó"
   ```
 
 
@@ -1841,7 +1841,7 @@ static isDigit(char: string): boolean
 
 **示例：** 
   ```js
-  var isdigit = I18n.Unicode.isDigit("1");  // isdigit = true
+  let isdigit = I18n.Unicode.isDigit("1");  // isdigit = true
   ```
 
 
@@ -1867,7 +1867,7 @@ static isSpaceChar(char: string): boolean
 
 **示例：** 
   ```js
-  var isspacechar = I18n.Unicode.isSpaceChar("a");  // isspacechar = false
+  let isspacechar = I18n.Unicode.isSpaceChar("a");  // isspacechar = false
   ```
 
 
@@ -1893,7 +1893,7 @@ static isWhitespace(char: string): boolean
 
 **示例：** 
   ```js
-  var iswhitespace = I18n.Unicode.isWhitespace("a");  // iswhitespace = false
+  let iswhitespace = I18n.Unicode.isWhitespace("a");  // iswhitespace = false
   ```
 
 
@@ -1919,7 +1919,7 @@ static isRTL(char: string): boolean
 
 **示例：** 
   ```js
-  var isrtl = I18n.Unicode.isRTL("a");  // isrtl = false
+  let isrtl = I18n.Unicode.isRTL("a");  // isrtl = false
   ```
 
 
@@ -1945,7 +1945,7 @@ static isIdeograph(char: string): boolean
 
 **示例：** 
   ```js
-  var isideograph = I18n.Unicode.isIdeograph("a");  // isideograph = false
+  let isideograph = I18n.Unicode.isIdeograph("a");  // isideograph = false
   ```
 
 
@@ -1971,7 +1971,7 @@ static isLetter(char: string): boolean
 
 **示例：** 
   ```js
-  var isletter = I18n.Unicode.isLetter("a");  // isletter = true
+  let isletter = I18n.Unicode.isLetter("a");  // isletter = true
   ```
 
 
@@ -1997,7 +1997,7 @@ static isLowerCase(char: string): boolean
 
 **示例：** 
   ```js
-  var islowercase = I18n.Unicode.isLowerCase("a");  // islowercase = true
+  let islowercase = I18n.Unicode.isLowerCase("a");  // islowercase = true
   ```
 
 
@@ -2023,7 +2023,7 @@ static isUpperCase(char: string): boolean
 
 **示例：** 
   ```js
-  var isuppercase = I18n.Unicode.isUpperCase("a");  // isuppercase = false
+  let isuppercase = I18n.Unicode.isUpperCase("a");  // isuppercase = false
   ```
 
 
@@ -2049,7 +2049,7 @@ static getType(char: string): string
 
 **示例：** 
   ```js
-  var type = I18n.Unicode.getType("a"); // type = "U_LOWERCASE_LETTER"
+  let type = I18n.Unicode.getType("a"); // type = "U_LOWERCASE_LETTER"
   ```
 
 
@@ -2082,7 +2082,7 @@ static unitConvert(fromUnit: UnitInfo, toUnit: UnitInfo, value: number, locale:
 
 **示例：** 
   ```js
-  var res = I18n.I18NUtil.unitConvert({unit: "cup", measureSystem: "US"}, {unit: "liter", measureSystem: "SI"}, 1000, "en-US", "long"); // res = 236.588 liters
+  let res = I18n.I18NUtil.unitConvert({unit: "cup", measureSystem: "US"}, {unit: "liter", measureSystem: "SI"}, 1000, "en-US", "long"); // res = 236.588 liters
   ```
 
 
@@ -2108,7 +2108,7 @@ static getDateOrder(locale: string): string
 
 **示例：** 
   ```js
-  var order = I18n.I18NUtil.getDateOrder("zh-CN");  // order = "y-L-d"
+  let order = I18n.I18NUtil.getDateOrder("zh-CN");  // order = "y-L-d"
   ```
 
 
@@ -2138,7 +2138,7 @@ getDisplayCountry(country: string, locale: string, sentenceCase?: boolean): stri
 
 **示例：** 
   ```js
-  var countryName = I18n.getDisplayCountry("zh-CN", "en-GB", true); // countryName = true
+  let countryName = I18n.getDisplayCountry("zh-CN", "en-GB", true); // countryName = true
   countryName = I18n.getDisplayCountry("zh-CN", "en-GB"); // countryName = true
   ```
 
@@ -2169,7 +2169,7 @@ getDisplayLanguage(language: string, locale: string, sentenceCase?: boolean): st
 
 **示例：** 
   ```js
-  var languageName = I18n.getDisplayLanguage("zh", "en-GB", true); // languageName = "Chinese"
+  let languageName = I18n.getDisplayLanguage("zh", "en-GB", true); // languageName = "Chinese"
   languageName = I18n.getDisplayLanguage("zh", "en-GB"); // languageName = "Chinese"
   ```
 
@@ -2192,7 +2192,7 @@ getSystemLanguage(): string
 
 **示例：** 
   ```js
-  var systemLanguage = I18n.getSystemLanguage(); // 返回当前系统语言
+  let systemLanguage = I18n.getSystemLanguage(); // 返回当前系统语言
   ```
 
 
@@ -2214,7 +2214,7 @@ getSystemRegion(): string
 
 **示例：** 
   ```js
-  var region = I18n.getSystemRegion(); // 返回当前系统地区
+  let region = I18n.getSystemRegion(); // 返回当前系统地区
   ```
 
 
@@ -2236,7 +2236,7 @@ getSystemLocale(): string
 
 **示例：** 
   ```js
-  var locale = I18n.getSystemLocale(); // 返回系统Locale
+  let locale = I18n.getSystemLocale(); // 返回系统Locale
   ```
 
 
@@ -2258,7 +2258,7 @@ is24HourClock(): boolean
 
 **示例：** 
   ```js
-  var is24HourClock = I18n.is24HourClock();
+  let is24HourClock = I18n.is24HourClock();
   ```
 
 
@@ -2289,7 +2289,7 @@ set24HourClock(option: boolean): boolean
 **示例：** 
   ```js
   // 将系统时间设置为24小时制
-  var success = I18n.set24HourClock(true);
+  let success = I18n.set24HourClock(true);
   ```
 
 
@@ -2321,9 +2321,9 @@ addPreferredLanguage(language: string, index?: number): boolean
 **示例：** 
   ```js
   // 将语言zh-CN添加到系统偏好语言列表中
-  var language = 'zh-CN';
-  var index = 0;
-  var success = I18n.addPreferredLanguage(language, index);
+  let language = 'zh-CN';
+  let index = 0;
+  let success = I18n.addPreferredLanguage(language, index);
   ```
 
 
@@ -2354,8 +2354,8 @@ removePreferredLanguage(index: number): boolean
 **示例：** 
   ```js
   // 删除系统偏好语言列表中的第一个偏好语言
-  var index = 0;
-  var success = I18n.removePreferredLanguage(index);
+  let index = 0;
+  let success = I18n.removePreferredLanguage(index);
   ```
 
 
@@ -2377,7 +2377,7 @@ getPreferredLanguageList(): Array<string>
 
 **示例：** 
   ```js
-  var preferredLanguageList = I18n.getPreferredLanguageList(); // 获取系统偏好语言列表
+  let preferredLanguageList = I18n.getPreferredLanguageList(); // 获取系统偏好语言列表
   ```
 
 
@@ -2399,7 +2399,7 @@ getFirstPreferredLanguage(): string
 
 **示例：** 
   ```js
-  var firstPreferredLanguage = I18n.getFirstPreferredLanguage();
+  let firstPreferredLanguage = I18n.getFirstPreferredLanguage();
   ```
 
 
diff --git a/zh-cn/application-dev/reference/apis/js-apis-intl.md b/zh-cn/application-dev/reference/apis/js-apis-intl.md
index ae08faf6705b09361342f0c46aff211294cbe2d4..f0f8b660be17993f46028d9ee08e976f7e9e2104 100644
--- a/zh-cn/application-dev/reference/apis/js-apis-intl.md
+++ b/zh-cn/application-dev/reference/apis/js-apis-intl.md
@@ -48,9 +48,9 @@ constructor()
 **示例：** 
   ```js
   // 默认构造函数使用系统当前locale创建Locale对象
-  var locale = new Intl.Locale()
+  let locale = new Intl.Locale()
   // 返回系统当前localel
-  var localeID = locale.toString()
+  let localeID = locale.toString()
   ```
 
 
@@ -72,8 +72,8 @@ constructor(locale: string, options?: LocaleOptions)
 **示例：** 
   ```js
   // 创建 "zh-CN" Locale对象
-  var locale = new Intl.Locale("zh-CN")
-  var localeID = locale.toString() // localeID = "zh-CN"
+  let locale = new Intl.Locale("zh-CN")
+  let localeID = locale.toString() // localeID = "zh-CN"
   ```
 
 
@@ -94,8 +94,8 @@ toString(): string
 **示例：** 
   ```js
   // 创建 "en-GB" Locale对象
-  var locale = new Intl.Locale("en-GB");
-  var localeID = locale.toString(); // localeID = "en-GB"
+  let locale = new Intl.Locale("en-GB");
+  let localeID = locale.toString(); // localeID = "en-GB"
   ```
 
 
@@ -116,16 +116,16 @@ maximize(): Locale
 **示例：** 
   ```js
   // 创建 "zh" Locale对象
-  var locale = new Intl.Locale("zh");
+  let locale = new Intl.Locale("zh");
   // 补齐Locale对象的脚本和地区
-  locale.maximize();
-  var localeID = locale.toString(); // localeID = "zh-Hans-CN"
+  let maximizedLocale = locale.maximize();
+  let localeID = maximizedLocale.toString(); // localeID = "zh-Hans-CN"
 
   // 创建 "en-US" Locale对象
   locale = new Intl.Locale("en-US");
   // 补齐Locale对象的脚本
-  locale.maximize();
-  localeID = locale.toString(); // localeID = "en-Latn-US"
+  maximizedLocale = locale.maximize();
+  localeID = maximizedLocale.toString(); // localeID = "en-Latn-US"
   ```
 
 
@@ -146,16 +146,16 @@ minimize(): Locale
 **示例：** 
   ```js
   // 创建 "zh-Hans-CN" Locale对象
-  var locale = new Intl.Locale("zh-Hans-CN");
+  let locale = new Intl.Locale("zh-Hans-CN");
   // 去除Locale对象的脚本和地区
-  locale.minimize();
-  var localeID = locale.toString(); // localeID = "zh"
+  let minimizedLocale = locale.minimize();
+  let localeID = minimizedLocale.toString(); // localeID = "zh"
 
   // 创建 "en-US" Locale对象
   locale = new Intl.Locale("en-US");
   // 去除Locale对象的地区
-  locale.minimize();
-  localeID = locale.toString(); // localeID = "en"
+  minimizedLocale = locale.minimize();
+  localeID = minimizedLocale.toString(); // localeID = "en"
   ```
 
 
@@ -189,7 +189,7 @@ constructor()
 **示例：** 
   ```js
   // 使用系统当前locale创建DateTimeFormat对象
-  var datefmt= new Intl.DateTimeFormat();
+  let datefmt= new Intl.DateTimeFormat();
   ```
 
 
@@ -211,14 +211,14 @@ constructor(locale: string | Array<string>, options?: DateTimeOptions)
 **示例：** 
   ```js
   // 使用 "zh-CN" locale创建DateTimeFormat对象，日期风格为full，时间风格为medium
-  var datefmt= new Intl.DateTimeFormat("zh-CN", { dateStyle: 'full', timeStyle: 'medium' });
+  let datefmt= new Intl.DateTimeFormat("zh-CN", { dateStyle: 'full', timeStyle: 'medium' });
   ```
 
 
 **示例：** 
   ```js
   // 使用 ["ban", "zh"] locale列表创建DateTimeFormat对象，因为ban为非法LocaleID，因此使用zh Locale创建DateTimeFormat对象
-  var datefmt= new Intl.DateTimeFormat(["ban", "zh"], { dateStyle: 'full', timeStyle: 'medium' });
+  let datefmt= new Intl.DateTimeFormat(["ban", "zh"], { dateStyle: 'full', timeStyle: 'medium' });
   ```
 
 
@@ -244,10 +244,10 @@ format(date: Date): string
 
 **示例：** 
   ```js
-  var date = new Date(2021, 11, 17, 3, 24, 0);
+  let date = new Date(2021, 11, 17, 3, 24, 0);
   // 使用 en-GB locale创建DateTimeFormat对象
-  var datefmt = new Intl.DateTimeFormat("en-GB");
-  var formattedDate = datefmt.format(date); // formattedDate "17/12/2021"
+  let datefmt = new Intl.DateTimeFormat("en-GB");
+  let formattedDate = datefmt.format(date); // formattedDate "17/12/2021"
 
   // 使用 en-GB locale创建DateTimeFormat对象，dateStyle设置为full，timeStyle设置为medium
   datefmt = new Intl.DateTimeFormat("en-GB", { dateStyle: 'full', timeStyle: 'medium' });
@@ -278,11 +278,11 @@ formatRange(startDate: Date, endDate: Date): string
 
 **示例：** 
   ```js
-  var startDate = new Date(2021, 11, 17, 3, 24, 0);
-  var endDate = new Date(2021, 11, 18, 3, 24, 0);
+  let startDate = new Date(2021, 11, 17, 3, 24, 0);
+  let endDate = new Date(2021, 11, 18, 3, 24, 0);
   // 使用 en-GB locale创建DateTimeFormat对象
-  var datefmt = new Intl.DateTimeFormat("en-GB");
-  var formattedDateRange = datefmt.formatRange(startDate, endDate); // formattedDateRange = "17/12/2021-18/12/2021"
+  let datefmt = new Intl.DateTimeFormat("en-GB");
+  let formattedDateRange = datefmt.formatRange(startDate, endDate); // formattedDateRange = "17/12/2021-18/12/2021"
   ```
 
 
@@ -302,11 +302,11 @@ resolvedOptions(): DateTimeOptions
 
 **示例：** 
   ```js
-  var datefmt = new Intl.DateTimeFormat("en-GB", { dateStyle: 'full', timeStyle: 'medium' });
+  let datefmt = new Intl.DateTimeFormat("en-GB", { dateStyle: 'full', timeStyle: 'medium' });
   // 返回DateTimeFormat对象的配置项
-  var options = datefmt.resolvedOptions();
-  var dateStyle = options.dateStyle; // dateStyle = "full"
-  var timeStyle = options.timeStyle; // timeStyle = "medium"
+  let options = datefmt.resolvedOptions();
+  let dateStyle = options.dateStyle; // dateStyle = "full"
+  let timeStyle = options.timeStyle; // timeStyle = "medium"
   ```
 
 
@@ -353,7 +353,7 @@ constructor()
 **示例：** 
   ```js
   // 使用系统当前locale创建NumberFormat对象
-  var numfmt = new Intl.NumberFormat();
+  let numfmt = new Intl.NumberFormat();
   ```
 
 
@@ -375,7 +375,7 @@ constructor(locale: string | Array<string>, options?: NumberOptions)
 **示例：** 
   ```js
   // 使用 en-GB locale创建NumberFormat对象，style设置为decimal，notation设置为scientific
-  var numfmt = new Intl.NumberFormat("en-GB", {style:'decimal', notation:"scientific"});
+  let numfmt = new Intl.NumberFormat("en-GB", {style:'decimal', notation:"scientific"});
   ```
 
 
@@ -403,8 +403,8 @@ format(number: number): string;
 **示例：** 
   ```js
   // 使用 ["en-GB", "zh"] locale列表创建NumberFormat对象，因为en-GB为合法LocaleID，因此使用en-GB创建NumberFormat对象
-  var numfmt = new Intl.NumberFormat(["en-GB", "zh"], {style:'decimal', notation:"scientific"});
-  var formattedNumber = numfmt.format(1223); // formattedNumber = 1.223E3
+  let numfmt = new Intl.NumberFormat(["en-GB", "zh"], {style:'decimal', notation:"scientific"});
+  let formattedNumber = numfmt.format(1223); // formattedNumber = 1.223E3
   ```
 
 
@@ -425,11 +425,11 @@ resolvedOptions(): NumberOptions
 
 **示例：** 
   ```js
-  var numfmt = new Intl.NumberFormat(["en-GB", "zh"], {style:'decimal', notation:"scientific"});
+  let numfmt = new Intl.NumberFormat(["en-GB", "zh"], {style:'decimal', notation:"scientific"});
   // 获取NumberFormat对象配置项
-  var options = numfmt.resolvedOptions();
-  var style = options.style; // style = decimal
-  var notation = options.notation // notation = scientific
+  let options = numfmt.resolvedOptions();
+  let style = options.style; // style = decimal
+  let notation = options.notation // notation = scientific
   ```
 
 
@@ -476,7 +476,7 @@ constructor()
 **示例：** 
   ```js
   // 使用系统locale创建Collator对象
-  var collator = new Intl.Collator();
+  let collator = new Intl.Collator();
   ```
 
 
@@ -498,7 +498,7 @@ constructor(locale: string | Array<string>, options?: CollatorOptions)
 **示例：** 
   ```js
   // 使用 zh-CN locale创建Collator对象，localeMatcher设置为lookup，usage设置为sort
-  var collator = new Intl.Collator("zh-CN", {localeMatcher: "lookup", usage: "sort"});
+  let collator = new Intl.Collator("zh-CN", {localeMatcher: "lookup", usage: "sort"});
   ```
 
 
@@ -526,9 +526,9 @@ compare(first: string, second: string): number
 **示例：** 
   ```js
   // 使用en-GB locale创建Collator对象
-  var collator = new Intl.Collator("en-GB");
+  let collator = new Intl.Collator("en-GB");
   // 比较 "first" 和 "second" 的先后顺序
-  var compareResult = collator.compare("first", "second"); // compareResult = -1
+  let compareResult = collator.compare("first", "second"); // compareResult = -1
   ```
 
 
@@ -548,11 +548,11 @@ resolvedOptions(): CollatorOptions
 
 **示例：** 
   ```js
-  var collator = new Intl.Collator("zh-Hans", { usage: 'sort', ignorePunctuation: 'true' });
+  let collator = new Intl.Collator("zh-Hans", { usage: 'sort', ignorePunctuation: true });
   // 获取Collator对象的配置项
-  var options = collator.resolvedOptions();
-  var usage = options.usage; // usage = "sort"
-  var ignorePunctuation = options.ignorePunctuation // ignorePunctuation = true
+  let options = collator.resolvedOptions();
+  let usage = options.usage; // usage = "sort"
+  let ignorePunctuation = options.ignorePunctuation // ignorePunctuation = true
   ```
 
 
@@ -566,7 +566,7 @@ resolvedOptions(): CollatorOptions
 | ----------------- | ------- | ---- | ---- | ---------------------------------------- |
 | localeMatcher     | string  | 是    | 是    | locale匹配算法，取值范围："best fit", "lookup"。 |
 | usage             | string  | 是    | 是    | 比较的用途，取值范围："sort", "search"。        |
-| sensitivity       | string  | 是    | 是    | 表示字符串中的哪些差异会导致非零结果值，取值范围："base", "accent", "case", "variant"。 |
+| sensitivity       | string  | 是    | 是    | 表示字符串中的哪些差异会导致非零结果值，取值范围："base", "accent", "case", "letiant"。 |
 | ignorePunctuation | boolean | 是    | 是    | 表示是否忽略标点符号，取值范围：true, false。        |
 | collation         | string  | 是    | 是    | 排序规则，取值范围："big5han", "compat", "dict", "direct", "ducet", "eor", "gb2312", "phonebk", "phonetic", "pinyin", "reformed", "searchjl", "stroke", "trad", "unihan", "zhuyin"。 |
 | numeric           | boolean | 是    | 是    | 是否使用数字排序，取值范围：true, false。          |
@@ -580,14 +580,14 @@ resolvedOptions(): CollatorOptions
 
 constructor()
 
-创建PluralRules对象。
+创建单复数对象来计算数字的单复数类别。
 
 **系统能力**：SystemCapability.Global.I18n
 
 **示例：** 
   ```js
   // 使用系统locale创建PluralRules对象
-  var pluralRules = new Intl.PluralRules();
+  let pluralRules = new Intl.PluralRules();
   ```
 
 
@@ -595,7 +595,7 @@ constructor()
 
 constructor(locale: string | Array<string>, options?: PluralRulesOptions)
 
-创建PluralRules对象。
+创建单复数对象来计算数字的单复数类别。
 
 **系统能力**：SystemCapability.Global.I18n
 
@@ -609,7 +609,7 @@ constructor(locale: string | Array<string>, options?: PluralRulesOptions)
 **示例：** 
   ```js
   // 使用 zh-CN locale创建PluralRules对象，localeMatcher设置为lookup，type设置为cardinal
-  var pluralRules= new Intl.PluralRules("zh-CN", {"localeMatcher": "lookup", "type": "cardinal"});
+  let pluralRules= new Intl.PluralRules("zh-CN", {"localeMatcher": "lookup", "type": "cardinal"});
   ```
 
 
@@ -636,9 +636,14 @@ select(n: number): string
 **示例：** 
   ```js
   // 使用 zh-Hans locale创建PluralRules对象
-  var pluralRules = new Intl.PluralRules("zh-Hans");
+  let zhPluralRules = new Intl.PluralRules("zh-Hans");
   // 计算 zh-Hans locale中数字1对应的单复数类别
-  var plural = pluralRules.select(1); // plural = other
+  let plural = zhPluralRules.select(1); // plural = other
+
+  // 使用 en-US locale创建PluralRules对象
+  let enPluralRules = new Intl.PluralRules("en-US");
+  // 计算 en-US locale中数字1对应的单复数类别
+  plural = enPluralRules.select(1); // plural = one
   ```
 
 
@@ -673,7 +678,7 @@ constructor()
 **示例：** 
   ```js
   // 使用系统locale创建RelativeTimeFormat对象
-  var relativetimefmt = new Intl.RelativeTimeFormat();
+  let relativetimefmt = new Intl.RelativeTimeFormat();
   ```
 
 
@@ -695,7 +700,7 @@ constructor(locale: string | Array<string>, options?: RelativeTimeFormatIn
 **示例：** 
   ```js
   // 使用 zh-CN locale创建RelativeTimeFormat对象，localeMatcher设置为lookup，numeric设置为always，style设置为long
-  var relativeTimeFormat = new Intl.RelativeTimeFormat("zh-CN", {"localeMatcher": "lookup", "numeric": "always", "style": "long"});
+  let relativeTimeFormat = new Intl.RelativeTimeFormat("zh-CN", {"localeMatcher": "lookup", "numeric": "always", "style": "long"});
   ```
 
 
@@ -723,9 +728,9 @@ format(value: number, unit: string): string
 **示例：** 
   ```js
   // 使用 zh-CN locale创建RelativeTimeFormat对象
-  var relativetimefmt = new Intl.RelativeTimeFormat("zh-CN");
+  let relativetimefmt = new Intl.RelativeTimeFormat("zh-CN");
   // 计算 zh-CN locale中数字3，单位quarter的本地化表示
-  var formatResult = relativetimefmt.format(3, "quarter")； // formatResult = "3个季度后"
+  let formatResult = relativetimefmt.format(3, "quarter"); // formatResult = "3个季度后"
   ```
 
 
@@ -753,8 +758,8 @@ formatToParts(value: number, unit: string): Array<object>
 **示例：** 
   ```js
   // 使用 en locale创建RelativeTimeFormat对象，numeric设置为auto
-  var relativetimefmt = new Intl.RelativeTimeFormat("en", {"numeric": "auto"});
-  var parts = relativetimefmt.formatToParts(10, "seconds"); // parts = [ {type: "literal", value: "in"}, {type: "integer", value: 10, unit: "second"}, {type: "literal", value: "seconds"} ]
+  let relativetimefmt = new Intl.RelativeTimeFormat("en", {"numeric": "auto"});
+  let parts = relativetimefmt.formatToParts(10, "seconds"); // parts = [ {type: "literal", value: "in"}, {type: "integer", value: 10, unit: "second"}, {type: "literal", value: "seconds"} ]
   ```
 
 
@@ -775,10 +780,10 @@ resolvedOptions(): RelativeTimeFormatResolvedOptions
 **示例：** 
   ```js
   // 使用 en-GB locale创建RelativeTimeFormat对象
-  var relativetimefmt= new Intl.RelativeTimeFormat("en-GB", { style: "short" });
+  let relativetimefmt= new Intl.RelativeTimeFormat("en-GB", { style: "short" });
   // 获取RelativeTimeFormat对象配置项
-  var options = relativetimefmt.resolvedOptions();
-  var style = options.style; // style = "short"
+  let options = relativetimefmt.resolvedOptions();
+  let style = options.style; // style = "short"
   ```