Angular window resize event

Angular window resize event

I would like to perform some tasks based on the window re-size event (on load and dynamically).
Currently I have my DOM as follows:

The event correctly fires
export class AppComponent {
onResize(event) {
console.log(event);
}
}

How do I retrieve the Width and Height from this event object?
Thanks.

Solutions/Answers:

Solution 1:

<div (window:resize)="onResize($event)"
onResize(event) {
  event.target.innerWidth;
}

or

@HostListener('window:resize', ['$event'])
onResize(event) {
  event.target.innerWidth;
}

Supported global targets are window, document, and body.

Until https://github.com/angular/angular/issues/13248 is implemented in Angular it is better for performance to subscribe to DOM events imperatively and use RXJS to reduce the amount of events as shown in some of the other answers.

Solution 2:

@Günter’s answer is correct. I just wanted to propose yet another method.

You could also add the host-binding inside the @Component()-decorator. You can put the event and desired function call in the host-metadata-property like so:

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
  host: {
    '(window:resize)': 'onResize($event)'
  }
})
export class AppComponent{
   onResize(event){
     event.target.innerWidth; // window width
   }
}

Solution 3:

The correct way to do this is to utilize the EventManager class to bind the event. This allows your code to work in alternative platforms, for example server side rendering with Angular Universal.

import { EventManager } from '@angular/platform-browser';
import { Observable } from 'rxjs/Observable';
import { Subject } from 'rxjs/Subject';
import { Injectable } from '@angular/core';

@Injectable()
export class ResizeService {

  get onResize$(): Observable<Window> {
    return this.resizeSubject.asObservable();
  }

  private resizeSubject: Subject<Window>;

  constructor(private eventManager: EventManager) {
    this.resizeSubject = new Subject();
    this.eventManager.addGlobalEventListener('window', 'resize', this.onResize.bind(this));
  }

  private onResize(event: UIEvent) {
    this.resizeSubject.next(<Window>event.target);
  }
}

Usage in a component is as simple as adding this service as a provider to your app.module and then importing it in the constructor of a component.

import { Component, OnInit } from '@angular/core';

@Component({
  selector: 'my-component',
  template: ``,
  styles: [``]
})
export class MyComponent implements OnInit {

  private resizeSubscription: Subscription;

  constructor(private resizeService: ResizeService) { }

  ngOnInit() {
    this.resizeSubscription = this.resizeService.onResize$
      .subscribe(size => console.log(size));
  }

  ngOnDestroy() {
    if (this.resizeSubscription) {
      this.resizeSubscription.unsubscribe();
    }
  }
}

Solution 4:

Here is a better way to do it. Based on Birowsky’s answer.

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Step 1: Create an angular service with RxJS Observables.

import { Injectable } from '@angular/core';
import { Observable, BehaviorSubject } from 'rxjs';

@Injectable()
export class WindowService {
    height$: Observable<number>;
    //create more Observables as and when needed for various properties
    hello: string = "Hello";
    constructor() {
        let windowSize$ = new BehaviorSubject(getWindowSize());

        this.height$ = (windowSize$.pluck('height') as Observable<number>).distinctUntilChanged();

        Observable.fromEvent(window, 'resize')
            .map(getWindowSize)
            .subscribe(windowSize$);
    }

}

function getWindowSize() {
    return {
        height: window.innerHeight
        //you can sense other parameters here
    };
};

Step 2: Inject the above service and subscribe to any of the Observables created within the service wherever you would like to receive the window resize event.

import { Component } from '@angular/core';
//import service
import { WindowService } from '../Services/window.service';

@Component({
    selector: 'pm-app',
    templateUrl: './componentTemplates/app.component.html',
    providers: [WindowService]
})
export class AppComponent { 

    constructor(private windowService: WindowService) {

        //subscribe to the window resize event
        windowService.height$.subscribe((value:any) => {
            //Do whatever you want with the value.
            //You can also subscribe to other observables of the service
        });
    }

}

A sound understanding of Reactive Programming will always help in overcoming difficult problems. Hope this helps someone.

Solution 5:

I know this was asked a long time ago, but there is a better way to do this now! I’m not sure if anyone will see this answer though. Obviously your imports:

import { fromEvent } from "rxjs/observable/fromEvent";
import { Observable } from "rxjs/Observable";
import { Subscription } from "rxjs/Subscription";

Then in your component:

resizeObservable$: Observable<Event>
resizeSubscription$: Subscription

ngOnInit() {
    this.resizeObservable$ = fromEvent(window, 'resize')
    this.resizeSubscription$ = this.resizeObservable$.subscribe( evt => {
      console.log('event: ', evt)
    })
}

Then be sure to unsubscribe on destroy!

ngOnDestroy() {
    this.resizeSubscription$.unsubscribe()
}

Solution 6:

I haven’t seen anyone talking about MediaMatcher of angular/cdk.

You can define a MediaQuery and attach a listener to it – then anywhere on your template (or ts) you can invoke stuff if the Matcher is matched.
LiveExample

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App.Component.ts

import {Component, ChangeDetectorRef} from '@angular/core';
import {MediaMatcher} from '@angular/cdk/layout';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  mobileQuery: MediaQueryList;

  constructor(changeDetectorRef: ChangeDetectorRef, media: MediaMatcher) {
    this.mobileQuery = media.matchMedia('(max-width: 600px)');
    this._mobileQueryListener = () => changeDetectorRef.detectChanges();
    this.mobileQuery.addListener(this._mobileQueryListener);
  }

  private _mobileQueryListener: () => void;

  ngOnDestroy() {
    this.mobileQuery.removeListener(this._mobileQueryListener);
  }

}

App.Component.Html

<div [class]="mobileQuery.matches ? 'text-red' : 'text-blue'"> I turn red on mobile mode 
</div>

App.Component.css

.text-red { 
   color: red;
}

.text-blue {
   color: blue;
}

source: https://material.angular.io/components/sidenav/overview