Description:update docs

Feature or Bugfix:Bugfix
Binary Source:No
Signed-off-by: Nyangzk <yangzhongkai@huawei.com>
Change-Id: Ic100bb4a64efc7248df5930da203dbf4b49d5da5

zh-cn/application-dev/reference/apis/js-apis-formextension.md

@@ -42,6 +42,7 @@ onCreate(want: Want): formBindingData.FormBindingData
 - 示例：
 
   ```
+  export default class MyFormExtension extends FormExtension {
       onCreate(want) {
           console.log('FormExtension onCreate, want:' + want.abilityName);
           let dataObj1 = {
@@ -51,6 +52,7 @@ onCreate(want: Want): formBindingData.FormBindingData
           let obj1 = formBindingData.createFormBindingData(dataObj1);
           return obj1;
       }
+  }
   ```
 
 ## onCastToNormal
@@ -68,9 +70,11 @@ onCastToNormal(formId: string): void
 - 示例：
 
   ```
+  export default class MyFormExtension extends FormExtension {
       onCastToNormal(formId) {
           console.log('FormExtension onCastToNormal, formId:' + formId);
       }
+  }
   ```
 
 ## onUpdate
@@ -88,6 +92,7 @@ onUpdate(formId: string): void
 - 示例：
 
   ```
+  export default class MyFormExtension extends FormExtension {
       onUpdate(formId) {
           console.log('FormExtension onUpdate, formId:' + formId);
           let obj2 = formBindingData.createFormBindingData({temperature:"22c", time:"22:00"});
@@ -97,6 +102,7 @@ onUpdate(formId: string): void
               }).catch((error) => {
               console.error('Operation updateForm failed. Cause: ' + error);});
       }
+  }
   ```
 
 ## onVisibilityChange
@@ -114,6 +120,7 @@ onVisibilityChange(newStatus: { [key: string]: number }): void
 - 示例：
 
   ```
+  export default class MyFormExtension extends FormExtension {
       onVisibilityChange(newStatus) {
           console.log('FormExtension onVisibilityChange, newStatus:' + newStatus);
           let obj2 = formBindingData.createFormBindingData({temperature:"22c", time:"22:00"});
@@ -127,6 +134,7 @@ onVisibilityChange(newStatus: { [key: string]: number }): void
                   console.error('Operation updateForm failed. Cause: ' + error);});
           }
       }
+  }
   ```
 
 ## onEvent
@@ -145,9 +153,11 @@ onEvent(formId: string, message: string): void
 - 示例：
 
   ```
+  export default class MyFormExtension extends FormExtension {
       onEvent(formId, message) {
           console.log('FormExtension onEvent, formId:' + formId + ", message:" + message);
       }
+  }
   ```
 
 ## onDestroy
@@ -165,7 +175,9 @@ onDestroy(formId: string): void
 - 示例：
 
   ```
+  export default class MyFormExtension extends FormExtension {
       onDestroy(formId) {
           console.log('FormExtension onDestroy, formId:' + formId);
       }
+  }
   ```
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