How to inject window into a service?

Question

I'm writing an Angular 2 service in TypeScript that will make use of localstorage. I want to inject a reference to the browser window object into my service since I don't want to reference any global variables like Angular 1.x $window.

How do I do that?

Answer 1

You can get window from injected document.

import { Inject } from '@angular/core';
import { DOCUMENT } from '@angular/common';

export class MyClass {

  constructor(@Inject(DOCUMENT) private document: Document) {
     this.window = this.document.defaultView;
  }

  check() {
    console.log(this.document);
    console.log(this.window);
  }

}

Answer 2

This is the shortest/cleanest answer that I've found working with Angular 4 AOT

Source: https://github.com/angular/angular/issues/12631#issuecomment-274260009

@Injectable()
export class WindowWrapper extends Window {}

export function getWindow() { return window; }

@NgModule({
  ...
  providers: [
    {provide: WindowWrapper, useFactory: getWindow}
  ]
  ...
})
export class AppModule {
  constructor(w: WindowWrapper) {
    console.log(w);
  }
}

Answer 3

It's also a good idea to mark the DOCUMENT as optional. Per the Angular docs:

Document might not be available in the Application Context when Application and Rendering Contexts are not the same (e.g. when running the application into a Web Worker).

Here's an example of using the DOCUMENT to see whether the browser has SVG support:

import { Optional, Component, Inject } from '@angular/core';
import { DOCUMENT } from '@angular/common'

...

constructor(@Optional() @Inject(DOCUMENT) document: Document) {
   this.supportsSvg = !!(
   document &&
   document.createElementNS &&
   document.createElementNS('http://www.w3.org/2000/svg', 'svg').createSVGRect
);

Answer 4

@maxisam thanks for ngx-window-token. I was doing something similar but switched to yours. This is my service for listening to window resize events and notifying subscribers.

import { Inject, Injectable } from '@angular/core';
import { BehaviorSubject } from 'rxjs/BehaviorSubject';
import { Observable } from 'rxjs/Observable';
import 'rxjs/add/observable/fromEvent';
import { WINDOW } from 'ngx-window-token';


export interface WindowSize {
    readonly width: number;
    readonly height: number;
}

@Injectable()
export class WindowSizeService {

    constructor( @Inject(WINDOW) private _window: any ) {
        Observable.fromEvent(_window, 'resize')
        .auditTime(100)
        .map(event => <WindowSize>{width: event['currentTarget'].innerWidth, height: event['currentTarget'].innerHeight})
        .subscribe((windowSize) => {
            this.windowSizeChanged$.next(windowSize);
        });
    }

    readonly windowSizeChanged$ = new BehaviorSubject<WindowSize>(<WindowSize>{width: this._window.innerWidth, height: this._window.innerHeight});
}

Short and sweet and works like a charm.

Answer 5

This is working for me currently (2018-03, angular 5.2 with AoT, tested in angular-cli and a custom webpack build):

First, create an injectable service that provides a reference to window:

import { Injectable } from '@angular/core';

// This interface is optional, showing how you can add strong typings for custom globals.
// Just use "Window" as the type if you don't have custom global stuff
export interface ICustomWindow extends Window {
    __custom_global_stuff: string;
}

function getWindow (): any {
    return window;
}

@Injectable()
export class WindowRefService {
    get nativeWindow (): ICustomWindow {
        return getWindow();
    }
}

Now, register that service with your root AppModule so it can be injected everywhere:

import { WindowRefService } from './window-ref.service';

@NgModule({        
  providers: [
    WindowRefService 
  ],
  ...
})
export class AppModule {}

and then later on where you need to inject window:

import { Component} from '@angular/core';
import { WindowRefService, ICustomWindow } from './window-ref.service';

@Component({ ... })
export default class MyCoolComponent {
    private _window: ICustomWindow;

    constructor (
        windowRef: WindowRefService
    ) {
        this._window = windowRef.nativeWindow;
    }

    public doThing (): void {
        let foo = this._window.XMLHttpRequest;
        let bar = this._window.__custom_global_stuff;
    }
...

You may also wish to add nativeDocument and other globals to this service in a similar way if you use these in your application.

---

edit: Updated with Truchainz suggestion. edit2: Updated for angular 2.1.2 edit3: Added AoT notes edit4: Adding any type workaround note edit5: Updated solution to use a WindowRefService which fixes an error I was getting when using previous solution with a different build edit6: adding example custom Window typing

Answer 6

Before the @Component declaration, you can do that too,

declare var window: any;

The compiler will actually let you then access the global window variable now since you declare it as an assumed global variable with type any.

I wouldn't suggest to access window everywhere in your application though, You should create services that access/modify the needed window attributes (and inject those services in your components) to scope what you can do with the window without letting them to modify the whole window object.