TypeScript definition for BeforeInstallPromptEvent

Question

TypeScript definition for BeforeInstallPromptEvent

Which data type is recommended to use with the beforeinstallprompt event?

I attempted to utilize the BeforeInstallPromptEvent type, but it resulted in an error:

export class PwaService {
  //promptEvent: BeforeInstallPromptEvent;
  promptEvent;
  constructor(private swUpdate: SwUpdate, platform: PlatformService) {
    if(platform.isBrowser()){
      swUpdate.available.subscribe(event =>  {
        /*if (askUserToUpdate()) {
          window.location.reload();
        }*/
      });
      window.addEventListener('beforeinstallprompt', event => {
        this.promptEvent = event;
      });
    }
  }

  install(): void {
    if(this.promptEvent){
      this.promptEvent.prompt();
    }
  }
}

angular typescript service-worker progressive-web-apps

Answer 1

Answer №1

The BeforeInstallPromptEvent is a unique Web API that is currently only supported by Chrome and Android browsers. It may not be considered stable by Google yet, so an official type definition in the TypeScript DOM library might not be available anytime soon.

If you want to use this event, you can define the type yourself in a .d.ts file. The following definition, based on comments from MDN, seems to work accurately in Chrome 68:

/**
 * The BeforeInstallPromptEvent is triggered at the Window.onbeforeinstallprompt handler
 * before a user is prompted to "install" a website to their mobile home screen.
 *
 * @deprecated Only supported on Chrome and Android WebView.
 */
interface BeforeInstallPromptEvent extends Event {

  /**
   * Returns an array of platform names where the event was dispatched.
   */
  readonly platforms: Array<string>;

  /**
   * Returns a Promise that resolves to either "accepted" or "dismissed".
   */
  readonly userChoice: Promise<{
    outcome: 'accepted' | 'dismissed',
    platform: string
  }>;

  /**
   * Allows developers to trigger the install prompt at their desired time.
   */
  prompt(): Promise<void>;

}

Answer 2

The BeforeInstallPromptEvent is a unique Web API that is currently only supported by Chrome and Android browsers. It may not be considered stable by Google yet, so an official type definition in the TypeScript DOM library might not be available anytime soon.

If you want to use this event, you can define the type yourself in a .d.ts file. The following definition, based on comments from MDN, seems to work accurately in Chrome 68:

/**
 * The BeforeInstallPromptEvent is triggered at the Window.onbeforeinstallprompt handler
 * before a user is prompted to "install" a website to their mobile home screen.
 *
 * @deprecated Only supported on Chrome and Android WebView.
 */
interface BeforeInstallPromptEvent extends Event {

  /**
   * Returns an array of platform names where the event was dispatched.
   */
  readonly platforms: Array<string>;

  /**
   * Returns a Promise that resolves to either "accepted" or "dismissed".
   */
  readonly userChoice: Promise<{
    outcome: 'accepted' | 'dismissed',
    platform: string
  }>;

  /**
   * Allows developers to trigger the install prompt at their desired time.
   */
  prompt(): Promise<void>;

}

Answer 3

Answer №2

Enhancement to the provided solution: make sure to include a key in WindowEventMap:

interface BeforeInstallPromptEvent extends Event {
  readonly platforms: string[];
  readonly userChoice: Promise<{
    outcome: "accepted" | "dismissed";
    platform: string;
  }>;
  prompt(): Promise<void>;
}

declare global {
  interface WindowEventMap {
    beforeinstallprompt: BeforeInstallPromptEvent;
  }
}

window.addEventListener("beforeinstallprompt", (e) => {}); // e is now properly typed

Take note that the declare global {} serves as a container for defining global elements in your code. Another option is to place it in an ambient file without any import/export keywords, eliminating the need for the wrapper. However, consolidating related code in one file is considered best practice.

Answer 4

Enhancement to the provided solution: make sure to include a key in WindowEventMap:

interface BeforeInstallPromptEvent extends Event {
  readonly platforms: string[];
  readonly userChoice: Promise<{
    outcome: "accepted" | "dismissed";
    platform: string;
  }>;
  prompt(): Promise<void>;
}

declare global {
  interface WindowEventMap {
    beforeinstallprompt: BeforeInstallPromptEvent;
  }
}

window.addEventListener("beforeinstallprompt", (e) => {}); // e is now properly typed

Take note that the declare global {} serves as a container for defining global elements in your code. Another option is to place it in an ambient file without any import/export keywords, eliminating the need for the wrapper. However, consolidating related code in one file is considered best practice.

Answer 5

Answer №3

One potential enhancement for the user interface is to define the UserChoice as a specific type. This promise object mirrors the shape of the one returned by the prompt() function:

type UserChoice = Promise<{
  outcome: 'accepted' | 'dismissed';
  platform: string;
}>;

interface BeforeInstallPromptEvent extends Event {
  readonly platforms: string[];
  readonly userChoice: UserChoice;
  prompt(): Promise<UserChoice>;
}

More information can be found here: https://developer.mozilla.org/en-US/docs/Web/API/BeforeInstallPromptEvent/prompt#return_value

Answer 6

One potential enhancement for the user interface is to define the UserChoice as a specific type. This promise object mirrors the shape of the one returned by the prompt() function:

type UserChoice = Promise<{
  outcome: 'accepted' | 'dismissed';
  platform: string;
}>;

interface BeforeInstallPromptEvent extends Event {
  readonly platforms: string[];
  readonly userChoice: UserChoice;
  prompt(): Promise<UserChoice>;
}

More information can be found here: https://developer.mozilla.org/en-US/docs/Web/API/BeforeInstallPromptEvent/prompt#return_value

TypeScript definition for BeforeInstallPromptEvent

Answer №1

Answer №2

Answer №3

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