iFrame resizer (consumer) for angular 2

iframe-resizer.ts

// add this directive to an iFrame element and pass a name of the source, and this will change the height based on the
// events passed from the iframe source. the name of the source, and type of the message are checked before making a
// change to the element width.
// expects an object like to have been sent through the window.postMessage() interface :

// {
//     type: 'resize',
//     source: 'some-iframe-content',
//     value: {
//         height: 200
//     }
// }

// <iframe src="some-iframe.html" iframe-resizer="some-iframe-content"></iframe>

import { Directive, OnDestroy, HostListener, ElementRef, Input } from '@angular/core';

@Directive({
    selector: '[iframe-resizer]'
})

export class IFrameResizerDirective implements OnDestroy {
    @Input('iframe-resizer') sourceName: string;

    constructor(private el: ElementRef) { }


    @HostListener('window:message', ['$event'])

    onMessage(event: any) {
        if ('undefined' !== typeof event.data &&
            'undefined' !== typeof event.data.type &&
             event.data.type === 'resize' &&
            'undefined' !== typeof event.data.source &&
             event.data.source === this.sourceName) {
                this.resizeIframe(event.data);

        }
    }

    resizeIframe(data) {
       if ('undefined' !== typeof data.value && 'undefined' !== typeof data.value.height) {
           if (this.el.nativeElement.clientHeight !== Number(data.value.height)) {
               this.el.nativeElement.style.height = data.value.height + 'px';
           }
       }
    }

    ngOnDestroy() {
        // TODO: destroy @HostListener watcher?
    }


}

Is this directive to be used with the IFrame Resize lib?
Can you give me an example of how to use it?
thank you so much

Can some one post how to use this directive ?
Thanks.

Will this work for multiple iframes on one page . I mean won't it give the heights of multiple iframes on window:message event and you will have to filter out the height with the id of the iframe.