# FormHost

> **NOTE**
> 
> The initial APIs of this module are supported since API version 8. Newly added APIs will be marked with a superscript to indicate their earliest API version.

Provides APIs related to the widget host.

## Modules to Import

```
import formHost from '@ohos.application.formHost';
```

## Required Permissions

ohos.permission.REQUIRE_FORM

ohos.permission.GET_BUNDLE_INFO_PRIVILEGED

## deleteForm

deleteForm(formId: string, callback: AsyncCallback<void>): void;

Deletes a widget. This API uses an asynchronous callback to return the result. After this API is called, the application can no longer use the widget, and the Widget Manager will not retain the widget information.

**System capability**

SystemCapability.Ability.Form

**Parameters**

| Name| Type   | Mandatory| Description   |
| ------ | ------ | ---- | ------- |
| formId | string | Yes  | ID of a widget.|
| callback | AsyncCallback<void> | Yes| Callback used to return the result.|

**Example**

  ```js
  var formId = "12400633174999288";
  formHost.deleteForm(formId, (error, data) => {
      if (error.code) {
          console.log('formHost deleteForm, error:' + JSON.stringify(error));
      }
  });
  ```

## deleteForm

deleteForm(formId: string): Promise<void>;

Deletes a widget. This API uses a promise to return the result. After this API is called, the application can no longer use the widget, and the Widget Manager will not retain the widget information.

**System capability**

SystemCapability.Ability.Form

**Parameters**

  | Name| Type   | Mandatory| Description   |
  | ------ | ------ | ---- | ------- |
  | formId | string | Yes  | ID of a widget.|

**Return value**

  | Type| Description|
  | -------- | -------- |
  | Promise<void> | Promise used to return the result indicating whether the API is successfully called.|

**Parameters**

  ```js
  var formId = "12400633174999288";
  formHost.deleteForm(formId).then(() => {
      console.log('formHost deleteForm success');
  }).catch((error) => {
      console.log('formHost deleteForm, error:' + JSON.stringify(error));
  });
  ```

## releaseForm

releaseForm(formId: string, callback: AsyncCallback<void>): void;

Releases a widget. This API uses an asynchronous callback to return the result. After this API is called, the application can no longer use the widget, but the Widget Manager still retains the widget cache and storage information.

**System capability**

SystemCapability.Ability.Form

**Parameters**

| Name| Type   | Mandatory| Description   |
| ------ | ------ | ---- | ------- |
| formId | string | Yes  | ID of a widget.|
| callback | AsyncCallback<void> | Yes| Callback used to return the result.|

**Example**

  ```js
  var formId = "12400633174999288";
  formHost.releaseForm(formId, (error, data) => {
      if (error.code) {
          console.log('formHost releaseForm, error:' + JSON.stringify(error));
      }
  });
  ```

## releaseForm

releaseForm(formId: string, isReleaseCache: boolean, callback: AsyncCallback<void>): void;

Releases a widget. This API uses an asynchronous callback to return the result. After this API is called, the application can no longer use the widget, but the Widget Manager retains the storage information about the widget and retains or releases the cache information based on the setting.

**System capability**

SystemCapability.Ability.Form

**Parameters**

| Name        | Type    | Mandatory| Description       |
| -------------- | ------  | ---- | ----------- |
| formId         | string  | Yes  | ID of a widget.    |
| isReleaseCache | boolean | Yes  | Whether to release the cache.|
| callback | AsyncCallback<void> | Yes| Callback used to return the result.|

**Example**

  ```js
  var formId = "12400633174999288";
  formHost.releaseForm(formId, true, (error, data) => {
      if (error.code) {
          console.log('formHost releaseForm, error:' + JSON.stringify(error));
      }
  });
  ```

## releaseForm

releaseForm(formId: string, isReleaseCache?: boolean): Promise<void>;

Releases a widget. This API uses a promise to return the result. After this API is called, the application can no longer use the widget, but the Widget Manager retains the storage information about the widget and retains or releases the cache information based on the setting.

**System capability**

SystemCapability.Ability.Form

**Parameters**

  | Name        | Type    | Mandatory| Description       |
  | -------------- | ------  | ---- | ----------- |
  | formId         | string  | Yes  | ID of a widget.    |
  | isReleaseCache | boolean | No  | Whether to release the cache.|

**Return value**

  | Type| Description|
  | -------- | -------- |
  | Promise<void> | Promise used to return the result indicating whether the API is successfully called.|

**Example**

  ```js
  var formId = "12400633174999288";
  formHost.releaseForm(formId, true).then(() => {
      console.log('formHost releaseForm success');
  }).catch((error) => {
      console.log('formHost releaseForm, error:' + JSON.stringify(error));
  });
  ```

## requestForm

requestForm(formId: string, callback: AsyncCallback<void>): void;

Requests a widget update. This API uses an asynchronous callback to return the result.

**System capability**

SystemCapability.Ability.Form

**Parameters**

| Name| Type   | Mandatory| Description   |
| ------ | ------ | ---- | ------- |
| formId | string | Yes  | ID of a widget.|
| callback | AsyncCallback<void> | Yes| Callback used to return the result.|

**Example**

  ```js
  var formId = "12400633174999288";
  formHost.requestForm(formId, (error, data) => {
      if (error.code) {
          console.log('formHost requestForm, error:' + JSON.stringify(error));
      }
  });
  ```

## requestForm

requestForm(formId: string): Promise<void>;

Requests a widget update. This API uses a promise to return the result.

**System capability**

SystemCapability.Ability.Form

**Parameters**

  | Name| Type   | Mandatory| Description   |
  | ------ | ------ | ---- | ------- |
  | formId | string | Yes  | ID of a widget.|

**Return value**

  | Type| Description|
  | -------- | -------- |
  | Promise<void> | Promise used to return the result indicating whether the API is successfully called.|

**Example**

  ```js
  var formId = "12400633174999288";
  formHost.requestForm(formId).then(() => {
      console.log('formHost requestForm success');
  }).catch((error) => {
      console.log('formHost requestForm, error:' + JSON.stringify(error));
  });
  ```

## castTempForm

castTempForm(formId: string, callback: AsyncCallback<void>): void;

Converts a temporary widget to a normal one. This API uses an asynchronous callback to return the result.

**System capability**

SystemCapability.Ability.Form

**Parameters**

| Name| Type   | Mandatory| Description   |
| ------ | ------ | ---- | ------- |
| formId | string | Yes  | ID of a widget.|
| callback | AsyncCallback<void> | Yes| Callback used to return the result.|

**Example**

  ```js
  var formId = "12400633174999288";
  formHost.castTempForm(formId, (error, data) => {
      if (error.code) {
          console.log('formHost castTempForm, error:' + JSON.stringify(error));
      }
  });
  ```

## castTempForm

castTempForm(formId: string): Promise<void>;

Converts a temporary widget to a normal one. This API uses a promise to return the result.

**System capability**

SystemCapability.Ability.Form

**Parameters**

  | Name| Type   | Mandatory| Description   |
  | ------ | ------ | ---- | ------- |
  | formId | string | Yes  | ID of a widget.|

**Return value**

  | Type| Description|
  | -------- | -------- |
  | Promise<void> | Promise used to return the result indicating whether the API is successfully called.|

**Example**

  ```js
  var formId = "12400633174999288";
  formHost.castTempForm(formId).then(() => {
      console.log('formHost castTempForm success');
  }).catch((error) => {
      console.log('formHost castTempForm, error:' + JSON.stringify(error));
  });
  ```

## notifyVisibleForms

notifyVisibleForms(formIds: Array<string>, callback: AsyncCallback<void>): void;

Instructs the widget framework to make a widget visible. This API uses an asynchronous callback to return the result. After this API is called, **onVisibilityChange** is invoked to notify the widget provider.

**System capability**

SystemCapability.Ability.Form

**Parameters**

| Name| Type   | Mandatory| Description   |
| ------ | ------ | ---- | ------- |
| formIds  | Array<string>       | Yes  | List of widget IDs.        |
| callback | AsyncCallback<void> | Yes| Callback used to return the result.|

**Example**

  ```js
  var formId = ["12400633174999288"];
  formHost.notifyVisibleForms(formId, (error, data) => {
      if (error.code) {
          console.log('formHost notifyVisibleForms, error:' + JSON.stringify(error));
      }
  });
  ```

## notifyVisibleForms

notifyVisibleForms(formIds: Array<string>): Promise<void>;

Instructs the widget framework to make a widget visible. This API uses a promise to return the result. After this API is called, **onVisibilityChange** is invoked to notify the widget provider.

**System capability**

SystemCapability.Ability.Form

**Parameters**

| Name| Type   | Mandatory| Description   |
| ------ | ------ | ---- | ------- |
| formIds | Array<string> | Yes  | List of widget IDs.|

**Return value**

  | Type| Description|
  | -------- | -------- |
  | Promise<void> | Promise used to return the result indicating whether the API is successfully called.|

**Example**

  ```js
  var formId = ["12400633174999288"];
  formHost.notifyVisibleForms(formId).then(() => {
      console.log('formHost notifyVisibleForms success');
  }).catch((error) => {
      console.log('formHost notifyVisibleForms, error:' + JSON.stringify(error));
  });
  ```

## notifyInvisibleForms

notifyInvisibleForms(formIds: Array<string>, callback: AsyncCallback<void>): void;

Instructs the widget framework to make a widget invisible. This API uses an asynchronous callback to return the result. After this API is called, **onVisibilityChange** is invoked to notify the widget provider.

**System capability**

SystemCapability.Ability.Form

**Parameters**

| Name| Type   | Mandatory| Description   |
| ------ | ------ | ---- | ------- |
| formIds  | Array<string>       | Yes  | List of widget IDs.        |
| callback | AsyncCallback<void> | Yes| Callback used to return the result.|

**Example**

  ```js
  var formId = ["12400633174999288"];
  formHost.notifyInvisibleForms(formId, (error, data) => {
      if (error.code) {
          console.log('formHost notifyInvisibleForms, error:' + JSON.stringify(error));
      }
  });
  ```

## notifyInvisibleForms

notifyInvisibleForms(formIds: Array<string>): Promise<void>;

Instructs the widget framework to make a widget invisible. This API uses a promise to return the result. After this API is called, **onVisibilityChange** is invoked to notify the widget provider.

**System capability**

SystemCapability.Ability.Form

**Parameters**

| Name| Type   | Mandatory| Description   |
| ------ | ------ | ---- | ------- |
| formIds | Array<string> | Yes  | List of widget IDs.|

**Return value**

  | Type| Description|
  | -------- | -------- |
  | Promise<void> | Promise used to return the result indicating whether the API is successfully called.|

**Example**

  ```js
  var formId = ["12400633174999288"];
  formHost.notifyInvisibleForms(formId).then(() => {
      console.log('formHost notifyInvisibleForms success');
  }).catch((error) => {
      console.log('formHost notifyInvisibleForms, error:' + JSON.stringify(error));
  });
  ```

## enableFormsUpdate

enableFormsUpdate(formIds: Array<string>, callback: AsyncCallback<void>): void;

Instructs the widget framework to make a widget updatable. This API uses an asynchronous callback to return the result. After this API is called, the widget is in the enabled state and can receive updates from the widget provider.

**System capability**

SystemCapability.Ability.Form

**Parameters**

| Name| Type   | Mandatory| Description   |
| ------ | ------ | ---- | ------- |
| formIds  | Array<string>       | Yes  | List of widget IDs.        |
| callback | AsyncCallback<void> | Yes| Callback used to return the result.|

**Example**

  ```js
  var formId = ["12400633174999288"];
  formHost.enableFormsUpdate(formId, (error, data) => {
      if (error.code) {
          console.log('formHost enableFormsUpdate, error:' + JSON.stringify(error));
      }
  });
  ```

## enableFormsUpdate

enableFormsUpdate(formIds: Array<string>): Promise<void>;

Instructs the widget framework to make a widget updatable. This API uses a promise to return the result. After this API is called, the widget is in the enabled state and can receive updates from the widget provider.

**System capability**

SystemCapability.Ability.Form

**Parameters**

| Name| Type   | Mandatory| Description   |
| ------ | ------ | ---- | ------- |
| formIds | Array<string> | Yes  | List of widget IDs.|

**Return value**

  | Type| Description|
  | -------- | -------- |
  | Promise<void> | Promise used to return the result indicating whether the API is successfully called.|

**Example**

  ```js
  var formId = ["12400633174999288"];
  formHost.enableFormsUpdate(formId).then(() => {
      console.log('formHost enableFormsUpdate success');
  }).catch((error) => {
      console.log('formHost enableFormsUpdate, error:' + JSON.stringify(error));
  });
  ```

## disableFormsUpdate

disableFormsUpdate(formIds: Array<string>, callback: AsyncCallback<void>): void;

Instructs the widget framework to make a widget not updatable. This API uses an asynchronous callback to return the result. After this API is called, the widget cannot receive updates from the widget provider.

**System capability**

SystemCapability.Ability.Form

**Parameters**

| Name| Type   | Mandatory| Description   |
| ------ | ------ | ---- | ------- |
| formIds  | Array<string>       | Yes  | List of widget IDs.        |
| callback | AsyncCallback<void> | Yes| Callback used to return the result.|

**Example**

  ```js
  var formId = ["12400633174999288"];
  formHost.disableFormsUpdate(formId, (error, data) => {
      if (error.code) {
          console.log('formHost disableFormsUpdate, error:' + JSON.stringify(error));
      }
  });
  ```

## disableFormsUpdate

disableFormsUpdate(formIds: Array<string>): Promise<void>;

Instructs the widget framework to make a widget not updatable. This API uses a promise to return the result. After this API is called, the widget cannot receive updates from the widget provider.

**System capability**

SystemCapability.Ability.Form

**Parameters**

| Name| Type   | Mandatory| Description   |
| ------ | ------ | ---- | ------- |
| formIds | Array<string> | Yes  | List of widget IDs.|

**Return value**

  | Type| Description|
  | -------- | -------- |
  | Promise<void> | Promise used to return the result indicating whether the API is successfully called.|

**Example**

  ```js
  var formId = ["12400633174999288"];
  formHost.disableFormsUpdate(formId).then(() => {
      console.log('formHost disableFormsUpdate success');
  }).catch((error) => {
      console.log('formHost disableFormsUpdate, error:' + JSON.stringify(error));
  });
  ```

## isSystemReady

isSystemReady(callback: AsyncCallback<void>): void;

Checks whether the system is ready. This API uses an asynchronous callback to return the result.

**System capability**

SystemCapability.Ability.Form

**Parameters**

| Name| Type   | Mandatory| Description   |
| ------ | ------ | ---- | ------- |
| callback | AsyncCallback<void> | Yes| Callback used to return the result.|

**Example**

  ```js
  var formId = "12400633174999288";
  formHost.isSystemReady((error, data) => {
      if (error.code) {
          console.log('formHost isSystemReady, error:' + JSON.stringify(error));
      }
  });
  ```

## isSystemReady

isSystemReady(): Promise<void>;

Checks whether the system is ready. This API uses a promise to return the result.

**System capability**

SystemCapability.Ability.Form

**Return value**

  | Type| Description|
  | -------- | -------- |
  | Promise<void> | Promise used to return the result indicating whether the API is successfully called.|

**Example**

  ```js
  var formId = "12400633174999288";
  formHost.isSystemReady().then(() => {
      console.log('formHost isSystemReady success');
  }).catch((error) => {
      console.log('formHost isSystemReady, error:' + JSON.stringify(error));
  });
  ```

## getAllFormsInfo

getAllFormsInfo(callback: AsyncCallback<Array<formInfo.FormInfo>>): void;

Obtains the widget information provided by all applications on the device. This API uses an asynchronous callback to return the result.

**System capability**

SystemCapability.Ability.Form

**Parameters**

  | Name| Type   | Mandatory| Description   |
  | ------ | ------ | ---- | ------- |
  | callback | AsyncCallback<Array<[FormInfo](./js-apis-formInfo.md#forminfo-1)>> | Yes| Callback used to return the widget information.|

**Example**

  ```js
  formHost.getAllFormsInfo((error, data) => {
      if (error.code) {
          console.log('formHost getAllFormsInfo, error:' + JSON.stringify(error));
      } else {
          console.log('formHost getAllFormsInfo, data:' + JSON.stringify(data));
      }
  });
  ```

## getAllFormsInfo

getAllFormsInfo(): Promise<Array<formInfo.FormInfo>>;


Obtains the widget information provided by all applications on the device. This API uses a promise to return the result.

**System capability**

SystemCapability.Ability.Form

**Return value**

| Type         | Description                               |
| :------------ | :---------------------------------- |
| Promise<Array<[FormInfo](./js-apis-formInfo.md#forminfo-1)>> | Promise used to return the widget information.|

**Example**

  ```js
  formHost.getAllFormsInfo().then((data) => {
      console.log('formHost getAllFormsInfo data:' + JSON.stringify(data));
  }).catch((error) => {
      console.log('formHost getAllFormsInfo, error:' + JSON.stringify(error));
  });
  ```

## getFormsInfo

getFormsInfo(bundleName: string, callback: AsyncCallback<Array<formInfo.FormInfo>>): void;


Obtains the widget information provided by a given application on the device. This API uses an asynchronous callback to return the result.

**System capability**

SystemCapability.Ability.Form

**Parameters**

  | Name| Type   | Mandatory| Description   |
  | ------ | ------ | ---- | ------- |
  | bundleName | string | Yes|  Bundle name of the target application.|
  | callback | AsyncCallback<Array<[FormInfo](./js-apis-formInfo.md#forminfo-1)>> | Yes| Callback used to return the widget information.|

**Example**

  ```js
  formHost.getFormsInfo("com.example.ohos.formjsdemo", (error, data) => {
      if (error.code) {
          console.log('formHost getFormsInfo, error:' + JSON.stringify(error));
      } else {
          console.log('formHost getFormsInfo, data:' + JSON.stringify(data));
      }
  });
  ```

## getFormsInfo

getFormsInfo(bundleName: string, moduleName: string, callback: AsyncCallback<Array<formInfo.FormInfo>>): void;


Obtains the widget information provided by a given application on the device. This API uses an asynchronous callback to return the result.

**System capability**

SystemCapability.Ability.Form

**Parameters**

  | Name| Type   | Mandatory| Description   |
  | ------ | ------ | ---- | ------- |
  | bundleName | string | Yes|  Bundle name of the target application.|
  | moduleName | string | Yes|  Module name.|
  | callback | AsyncCallback<Array<[FormInfo](./js-apis-formInfo.md#forminfo-1)>> | Yes| Callback used to return the widget information.|

**Example**

  ```js
  formHost.getFormsInfo("com.example.ohos.formjsdemo", "entry", (error, data) => {
      if (error.code) {
          console.log('formHost getFormsInfo, error:' + JSON.stringify(error));
      } else {
          console.log('formHost getFormsInfo, data:' + JSON.stringify(data));
      }
  });
  ```

## getFormsInfo

getFormsInfo(bundleName: string, moduleName?: string): Promise<Array<formInfo.FormInfo>>;


Obtains the widget information provided by a given application on the device. This API uses a promise to return the result.

**System capability**

SystemCapability.Ability.Form

**Parameters**

  | Name| Type   | Mandatory| Description   |
  | ------ | ------ | ---- | ------- |
  | bundleName | string | Yes|  Bundle name of the target application.|
  | moduleName | string | No|  Module name.|

**Return value**

| Type         | Description                               |
| :------------ | :---------------------------------- |
| Promise<Array<[FormInfo](./js-apis-formInfo.md#forminfo-1)>> | Promise used to return the widget information.|

**Example**

  ```js
  formHost.getFormsInfo("com.example.ohos.formjsdemo", "entry").then((data) => {
      console.log('formHost getFormsInfo, data:' + JSON.stringify(data));
  }).catch((error) => {
      console.log('formHost getFormsInfo, error:' + JSON.stringify(error));
  });
  ```

## deleteInvalidForms

deleteInvalidForms(formIds: Array<string>, callback: AsyncCallback<number>): void;

Deletes invalid widgets from the list. This API uses an asynchronous callback to return the result.

**System capability**

SystemCapability.Ability.Form

**Parameters**

| Name| Type   | Mandatory| Description   |
| ------ | ------ | ---- | ------- |
| formIds | Array<string> | Yes  | List of valid widget IDs.|
| callback | AsyncCallback<number> | Yes| Callback used to return the number of widgets deleted.|

**Example**

  ```js
  var formIds = new Array("12400633174999288", "12400633174999289");
  formHost.deleteInvalidForms(formIds, (error, data) => {
      if (error.code) {
          console.log('formHost deleteInvalidForms, error:' + JSON.stringify(error));
      } else {
          console.log('formHost deleteInvalidForms, data:' + JSON.stringify(data));
      }
  });
  ```

## deleteInvalidForms

deleteInvalidForms(formIds: Array<string>): Promise<number>;

Deletes invalid widgets from the list. This API uses a promise to return the result.

**System capability**

SystemCapability.Ability.Form

**Parameters**

| Name| Type   | Mandatory| Description   |
| ------ | ------ | ---- | ------- |
| formIds | Array<string> | Yes  | List of valid widget IDs.|

**Return value**

| Type         | Description                               |
| :------------ | :---------------------------------- |
| Promise<number> | Promise used to return the number of widgets deleted.|

**Example**

  ```js
  var formIds = new Array("12400633174999288", "12400633174999289");
  formHost.deleteInvalidForms(formIds).then((data) => {
      console.log('formHost deleteInvalidForms, data:' + JSON.stringify(data));
  }).catch((error) => {
      console.log('formHost deleteInvalidForms, error:' + JSON.stringify(error));
  });
  ```

## acquireFormState

acquireFormState(want: Want, callback: AsyncCallback<formInfo.FormStateInfo>): void;

Obtains the widget state. This API uses an asynchronous callback to return the result.

**System capability**

SystemCapability.Ability.Form

**Parameters**

| Name| Type   | Mandatory| Description   |
| ------ | ------ | ---- | ------- |
| want | [Want](js-apis-application-Want.md) | Yes  | **Want** information carried to query the widget state.|
| callback | AsyncCallback<[FormStateInfo](js-apis-formInfo.md#formstateinfo)> | Yes| Callback used to return the widget state.|

**Example**

  ```js
  var want = {
      "deviceId": "",
      "bundleName": "ohos.samples.FormApplication",
      "abilityName": "FormAbility",
      "parameters": {
          "ohos.extra.param.key.module_name": "entry",
          "ohos.extra.param.key.form_name": "widget",
          "ohos.extra.param.key.form_dimension": 2
      }
  };
  formHost.acquireFormState(want, (error, data) => {
      if (error.code) {
          console.log('formHost acquireFormState, error:' + JSON.stringify(error));
      } else {
          console.log('formHost acquireFormState, data:' + JSON.stringify(data));
      }
  });
  ```

## acquireFormState

acquireFormState(want: Want): Promise<formInfo.FormStateInfo>;

Obtains the widget state. This API uses a promise to return the result.

**Parameters**

| Name| Type   | Mandatory| Description   |
| ------ | ------ | ---- | ------- |
| want   | [Want](js-apis-application-Want.md) | Yes  | **Want** information carried to query the widget state.|

**Return value**

| Type         | Description                               |
| :------------ | :---------------------------------- |
| Promise<[FormStateInfo](js-apis-formInfo.md#formstateinfo)> | Promise used to return the widget state.|

**System capability**

SystemCapability.Ability.Form

**Example**

  ```js
  var want = {
      "deviceId": "",
      "bundleName": "ohos.samples.FormApplication",
      "abilityName": "FormAbility",
      "parameters": {
          "ohos.extra.param.key.module_name": "entry",
          "ohos.extra.param.key.form_name": "widget",
          "ohos.extra.param.key.form_dimension": 2
      }
  };
  formHost.acquireFormState(want).then((data) => {
      console.log('formHost acquireFormState, data:' + JSON.stringify(data));
  }).catch((error) => {
      console.log('formHost acquireFormState, error:' + JSON.stringify(error));
  });
  ```

## on("formUninstall")

on(type: "formUninstall", callback: Callback<string>): void;

Subscribes to widget uninstall events.

**System capability**

SystemCapability.Ability.Form

**Parameters**

| Name| Type   | Mandatory| Description   |
| ------ | ------ | ---- | ------- |
| type | string | Yes  | Type of event to subscribe to. The value **formUninstall** indicates a widget uninstallation event.|
| callback | Callback<string> | Yes| Callback used for event subscription.|

**Example**

  ```js
  let callback = function(formId) {
      console.log('formHost on formUninstall, formId:' + formId);
  }
  formHost.on("formUninstall", callback);
  ```

## off("formUninstall")

off(type: "formUninstall", callback?: Callback<string>): void;

Unsubscribes from widget uninstall events.

**System capability**

SystemCapability.Ability.Form

**Parameters**

| Name| Type   | Mandatory| Description   |
| ------ | ------ | ---- | ------- |
| type | string | Yes  | Type of event to subscribe to. The value **formUninstall** indicates a widget uninstallation event.|
| callback | Callback<string> | No| Callback used for event unsubscription. If it is left unspecified, it indicates the callback for all the events that have been subscribed.|

**Example**

  ```js
  let callback = function(formId) {
      console.log('formHost on formUninstall, formId:' + formId);
  }
  formHost.off("formUninstall", callback);
  ```

## notifyFormsVisible

notifyFormsVisible(formIds: Array<string>, isVisible: boolean, callback: AsyncCallback<void>): void;

Instructs the widgets to make themselves visible. This API uses an asynchronous callback to return the result.

**System capability**

SystemCapability.Ability.Form

**Parameters**

| Name| Type   | Mandatory| Description   |
| ------ | ------ | ---- | ------- |
| formIds | Array<string> | Yes  | List of widget IDs.|
| isVisible | boolean | Yes  | Whether to be visible.|
| callback | AsyncCallback<void> | Yes| Callback used to return the result.|

**Example**

  ```js
  var formIds = new Array("12400633174999288", "12400633174999289");
  formHost.notifyFormsVisible(formIds, true, (error, data) => {
      if (error.code) {
          console.log('formHost notifyFormsVisible, error:' + JSON.stringify(error));
      }
  });
  ```

## notifyFormsVisible

notifyFormsVisible(formIds: Array<string>, isVisible: boolean): Promise<void>;

Instructs the widgets to make themselves visible. This API uses a promise to return the result.

**System capability**

SystemCapability.Ability.Form

**Parameters**

  | Name| Type   | Mandatory| Description   |
  | ------ | ------ | ---- | ------- |
  | formIds | Array<string> | Yes  | List of widget IDs.|
  | isVisible | boolean | Yes  | Whether to be visible.|

**Return value**

  | Type| Description|
  | -------- | -------- |
  | Promise<void> | Promise used to return the result indicating whether the API is successfully called.|

**Example**

  ```js
  var formIds = new Array("12400633174999288", "12400633174999289");
  formHost.notifyFormsVisible(formIds, true).then(() => {
      console.log('formHost notifyFormsVisible success');
  }).catch((error) => {
      console.log('formHost notifyFormsVisible, error:' + JSON.stringify(error));
  });
  ```

## notifyFormsEnableUpdate

notifyFormsEnableUpdate(formIds: Array<string>, isEnableUpdate: boolean, callback: AsyncCallback<void>): void;

Instructs the widgets to enable or disable updates. This API uses an asynchronous callback to return the result.

**System capability**

SystemCapability.Ability.Form

**Parameters**

| Name| Type   | Mandatory| Description   |
| ------ | ------ | ---- | ------- |
| formIds | Array<string> | Yes  | List of widget IDs.|
| isEnableUpdate | boolean | Yes  | Whether to enable update.|
| callback | AsyncCallback<void> | Yes| Callback used to return the result.|

**Example**

  ```js
  var formIds = new Array("12400633174999288", "12400633174999289");
  formHost.notifyFormsEnableUpdate(formIds, true, (error, data) => {
      if (error.code) {
          console.log('formHost notifyFormsEnableUpdate, error:' + JSON.stringify(error));
      }
  });
  ```

## notifyFormsEnableUpdate

notifyFormsEnableUpdate(formIds: Array<string>, isEnableUpdate: boolean): Promise<void>;

Instructs the widgets to enable or disable updates. This API uses a promise to return the result.

**System capability**

SystemCapability.Ability.Form

**Parameters**

  | Name| Type   | Mandatory| Description   |
  | ------ | ------ | ---- | ------- |
  | formIds | Array<string> | Yes  | List of widget IDs.|
  | isEnableUpdate | boolean | Yes  | Whether to enable update.|

**Return value**

  | Type| Description|
  | -------- | -------- |
  | Promise<void> | Promise used to return the result indicating whether the API is successfully called.|

**Example**

  ```js
  var formIds = new Array("12400633174999288", "12400633174999289");
  formHost.notifyFormsEnableUpdate(formIds, true).then(() => {
      console.log('formHost notifyFormsEnableUpdate success');
  }).catch((error) => {
      console.log('formHost notifyFormsEnableUpdate, error:' + JSON.stringify(error));
  });
  ```