# String String 全局对象是一个用于字符串或一个字符序列的构造函数。 字符串字面量采取以下形式： ```ts 'string text' "string text" "中文/汉语" "español" "English " "हिन्दी" "العربية" "português" "বাংলা" "русский" "日本語" "ਪੰਜਾਬੀ" "한국어" ``` ## 实例属性 ### length ```ts const x = "Mozilla"; const empty = ""; console.log("Mozilla is " + x.length + " code units long"); /* "Mozilla is 7 code units long" */ console.log("The empty string is has a length of " + empty.length); /* "The empty string is has a length of 0" */ ``` ## 实例方法 ### includes(searchString, position?) ```ts const str = 'To be, or not to be, that is the question.'; console.log(str.includes('To be')); // true console.log(str.includes('question')); // true console.log(str.includes('nonexistent')); // false console.log(str.includes('To be', 1)); // false console.log(str.includes('TO BE')); // false ``` ### endsWith(searchString, endPosition?) ```ts const str1 = 'Cats are the best!'; console.log(str1.endsWith('best!')); // expected output: true console.log(str1.endsWith('best', 17)); // expected output: true const str2 = 'Is this a question?'; console.log(str2.endsWith('question')); // expected output: false ``` ### repeat(count) ```ts "abc".repeat(0) // "" "abc".repeat(1) // "abc" "abc".repeat(2) // "abcabc" "abc".repeat(3.5) // "abcabcabc" 参数 count 将会被自动转换成整数。 ``` ### startsWith(searchString, position?) ### at(index) ```ts const sentence = 'The quick brown fox jumps over the lazy dog.'; let index = 5; console.log(`Using an index of ${index} the character returned is ${sentence.at(index)}`); // expected output: "Using an index of 5 the character returned is u" index = -4; console.log(`Using an index of ${index} the character returned is ${sentence.at(index)}`); // expected output: "Using an index of -4 the character returned is d" ``` ### charAt(pos) ```ts const anyString = "Brave new world"; console.log("The character at index 0 is '" + anyString.charAt(0) + "'"); // The character at index 0 is 'B' console.log("The character at index 1 is '" + anyString.charAt(1) + "'"); // The character at index 1 is 'r' console.log("The character at index 2 is '" + anyString.charAt(2) + "'"); // The character at index 2 is 'a' console.log("The character at index 3 is '" + anyString.charAt(3) + "'"); // The character at index 3 is 'v' console.log("The character at index 4 is '" + anyString.charAt(4) + "'"); // The character at index 4 is 'e' console.log("The character at index 999 is '" + anyString.charAt(999) + "'"); // The character at index 999 is '' ``` ### charCodeAt(index) ```ts const sentence = 'The quick brown fox jumps over the lazy dog.'; const index = 4; console.log(`The character code ${sentence.charCodeAt(index)} is equal to ${sentence.charAt(index)}`); // expected output: "The character code 113 is equal to q" ``` ### fromCharCode(...codes : number[]):string ```ts console.log(String.fromCharCode(189, 43, 190, 61)); // expected output: "½+¾=" console.log(String.fromCharCode(189, 165999, 190, 61)); // expected output: "½衯¾=" ``` ### concat(...strings) ```ts let hello = 'Hello, ' console.log(hello.concat('Kevin', '. Have a nice day.')) // Hello, Kevin. Have a nice day. ``` ### indexOf(searchString, position?) ```ts const paragraph = 'The quick brown fox jumps over the lazy dog. If the dog barked, was it really lazy?'; const searchTerm = 'dog'; const indexOfFirst = paragraph.indexOf(searchTerm); console.log(`The index of the first "${searchTerm}" from the beginning is ${indexOfFirst}`); // expected output: "The index of the first "dog" from the beginning is 40" console.log(`The index of the 2nd "${searchTerm}" is ${paragraph.indexOf(searchTerm, (indexOfFirst + 1))}`); // expected output: "The index of the 2nd "dog" is 52" ``` ### padEnd padEnd() 方法会用一个字符串填充当前字符串（如果需要的话则重复填充），返回填充后达到指定长度的字符串。从当前字符串的末尾（右侧）开始填充。 **平台差异说明** |JavaScript|Kotlin|Swift| |:-:|:-:|:-:| |√|√|√ `(3.6.11+)`| ```ts const str1 = 'Breaded Mushrooms'; console.log(str1.padEnd(25, '.')); // expected output: "Breaded Mushrooms........" const str2 = '200'; console.log(str2.padEnd(5)); // expected output: "200 " ``` ### padStart padStart() 方法用另一个字符串填充当前字符串 (如果需要的话，会重复多次)，以便产生的字符串达到给定的长度。从当前字符串的左侧开始填充。 **平台差异说明** |JavaScript|Kotlin|Swift| |:-:|:-:|:-:| |√|√|√ `(3.6.11+)`| ```ts const str1 = '5'; console.log(str1.padStart(2, '0')); // expected output: "05" ``` ### lastIndexOf(searchString, position?) ### match(regexp : string | RegExp) : RegExpMatchArray | null; ### replace(searchValue, replaceValue) ```ts const p = 'The quick brown fox jumps over the lazy dog. If the dog reacted, was it really lazy?'; console.log(p.replace('dog', 'monkey')); // expected output: "The quick brown fox jumps over the lazy monkey. If the dog reacted, was it really lazy?" const regex = /Dog/i; console.log(p.replace(regex, 'ferret')); // expected output: "The quick brown fox jumps over the lazy ferret. If the dog reacted, was it really lazy?" ``` ### replace(searchValue, replacer) ```ts // 不包含捕捉组的示例 let a = "The quick brown fox jumps over the lazy dog. If the dog reacted, was it really lazy?" let b = a.replace(RegExp("fox"),function(match: string, offset: number, string: string):string{ console.log("match",match) console.log("offset",offset) console.log("string",string) return "cat" }) console.log("b:",b) // 包含一个捕获组的示例。注意，目前android仅支持最多五个捕获组 let a1 = "The quick brown fox jumps over the lazy dog. If the dog reacted, was it really lazy?" let b1 = a1.replace(RegExp("(fox)"),function(match: string,p1: string, offset: number, string: string):string{ console.log("match",match) console.log("p1",p1) console.log("offset",offset) console.log("string",string) return "cat" }) console.log("b1",b1) ``` ### search(regexp) ```ts const paragraph = 'The quick brown fox jumps over the lazy dog. If the dog barked, was it really lazy?'; // any character that is not a word character or whitespace const regex = /[^\w\s]/g; console.log(paragraph.search(regex)); // expected output: 43 console.log(paragraph[paragraph.search(regex)]); // expected output: "." ``` ### slice(start?, end?) ```ts const str = 'The quick brown fox jumps over the lazy dog.'; console.log(str.slice(31)); // expected output: "the lazy dog." console.log(str.slice(4, 19)); // expected output: "quick brown fox" ``` ### split(separator, limit?) ```ts const str = 'The quick brown fox jumps over the lazy dog.'; const words = str.split(' '); console.log(words[3]); // expected output: "fox" const chars = str.split(''); console.log(chars[8]); // expected output: "k" ``` ### substring(start, end?) **bug&tips** 当前版本android平台 start 与 end 参数声明为Int, 需要将number 参数转换为int ```uts let a = 1 let b = 2 // 临时解决办法 "hello uts".substring(a.toInt(),b.toInt()) ``` 这个问题后续会修复 ### toLowerCase() ```ts console.log('中文简体 zh-CN || zh-Hans'.toLowerCase()); // 中文简体 zh-cn || zh-hans ​console.log( "ALPHABET".toLowerCase() ); // "alphabet" ``` ### toUpperCase() ```ts const sentence = 'The quick brown fox jumps over the lazy dog.'; console.log(sentence.toUpperCase()); // expected output: "THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG." ``` ### trim() ### padStart(targetLength, padString?) ### padEnd(targetLength, padString?) ### includes(searchString, position?) ### endsWith(searchString, endPosition?) ### repeat(count) ### startsWith(searchString, position?) ### at(index)