问动态更改typescript/angular4中iframe的高度

EN

import { Directive , ElementRef , OnInit , Renderer } from '@angular/core';
@Directive({
selector: '[iframeAutoHeight]'
})
export class IframeAutoHeightDirective implements OnInit {
private el: any;
private renderer: Renderer;
private prevHeight: number;
private sameCount: number;

constructor(_elementRef: ElementRef, _renderer: Renderer) {
    this.el = _elementRef.nativeElement;
    this.renderer = _renderer;
}

ngOnInit() {
    const self = this;
    if (this.el.tagName === 'IFRAME') {
        this.renderer.listen(this.el, 'load', () => {
            self.prevHeight = 0;
            self.sameCount = 0;
            setTimeout(() => {
                self.setHeight();
            }, 50);
        });
    }
}

setHeight() {
    const self = this;
    if (this.el.contentWindow.document.body.scrollHeight !== this.prevHeight) {
        this.sameCount = 0;
        this.prevHeight = this.el.contentWindow.document.body.scrollHeight;
        this.renderer.setElementStyle(
            self.el,
            'height',
            this.el.contentWindow.document.body.scrollHeight  + 'px'
        );
        setTimeout(() => {
            self.setHeight();
        }, 50);

    } else {
        this.sameCount++;
        if (this.sameCount < 2) {
            setTimeout(() => {
                self.setHeight();
            }, 50);
        }
    }
}
}