update zh-cn/application-dev/reference/apis/js-apis-system-parameter.md.

Signed-off-by: Nzengyawen <zengyawen1@huawei.com>

zh-cn/application-dev/reference/apis/js-apis-system-parameter.md

@@ -13,7 +13,7 @@ import parameter from '@ohos.systemParameter'
 
 ## parameter.getSync
 
-getSync(key: string, def?: string)
+getSync(key: string, def?: string): string
 
 获取系统属性Key对应的值。
 
@@ -46,7 +46,7 @@ try {
 
 ## parameter.get
 
-get(key: string, callback: AsyncCallback<string>)
+get(key: string, callback: AsyncCallback<string>): void
 
 获取系统属性Key对应的值。
 
@@ -77,7 +77,7 @@ try {
 
 ## parameter.get
 
-get(key: string, def: string, callback: AsyncCallback<string>)
+get(key: string, def: string, callback: AsyncCallback<string>): void
 
 获取系统属性Key对应的值。
 
@@ -110,7 +110,7 @@ try {
 
 ## parameter.get
 
-get(key: string, def?: string)
+get(key: string, def?: string): Promise<string>
 
 获取系统属性Key对应的值。
 
@@ -147,7 +147,7 @@ try {
 
 ## parameter.setSync
 
-setSync(key: string, value: string)
+setSync(key: string, value: string): void
 
 设置系统属性Key对应的值。
 
@@ -173,7 +173,7 @@ try {
 
 ## parameter.set(key: string, value: string, callback: AsyncCallback<void>)
 
-set(key: string, value: string, callback: AsyncCallback<void>)
+set(key: string, value: string, callback: AsyncCallback<void>): void
 
 设置系统属性Key对应的值。
 
@@ -205,7 +205,7 @@ try {
 
 ## parameter.set(key: string, def?: string)
 
-set(key: string, def?: string)
+set(key: string, def?: string): Promise<string>
 
 设置系统属性Key对应的值。