Angular2, view not updating after variable changes in settimeout

Question

I am trying to setup my first angular2 application as an experiment and am using the latest beta release.

I am facing a weird issue where the variable i am using in

Answer 1

I had a very similar problem to the OP where even in a basic Angular2 setup changes to bound properties would not be reflected by the view automatically. At this point in time we're using Angular2 2.0.0-rc.6. There was no error message.

In the end I found the culprit to be a reference to es6-promise.js, which was 'required' by a third party component we use. Somehow this interfered with the core-js reference we are using which is suggested with rc6 in some of the Angular2 tutorials.

As soon as I got rid of the es6-promise.js reference, the view updated correctly after changing a property on my component (via Promise or timeout).

Hope this helps somebody some day.

Answer 2

In Angular2 (~2.1.2) another way to make it work is through the ChangeDetectorRef class. The original question code would look like this:

import { 
  ChangeDetectorRef
  // ... other imports here
} from '@angular/core';

 @Component({
    selector: "my-app",
    bindings: []
})

@View({
    templateUrl: "templates/main.component.html",
    styleUrls: ['styles/out/components/main.component.css']
})

export class MainComponent {

    public test2 = "initial text";

    constructor(private cd: ChangeDetectorRef) {
        setTimeout(() => {
            this.test2 = "updated text"; 

            // as stated by the angular team: the following is required, otherwise the view will not be updated
            this.cd.markForCheck();

        }, 500);
    }
}

Answer 3

As Vlado said, it should work ;-)

I think that the angular2-polyfills.js library should be included into your page. I can't see it. This file is essentially a mashup of zone.js and reflect-metadata. Zones take part of the detection of updates.

You could have a look at this video where Bryan Ford explains what it is: https://www.youtube.com/watch?v=3IqtmUscE_U.

Hope it helps you, Thierry

Answer 4

That should work. Do you have any other errors in console?

@Component({
 selector: 'my-app',
 template: `<h1>Hello {{title}}</h1>`
})
export class App {
 public title: string = "World";
 constructor() {
   setTimeout(() => {
    this.title = "Brave New World"
   }, 1000);)
 }
}

Look at this Plunker: http://plnkr.co/edit/XaL4GoqFd9aisOYIhuXq?p=preview