angular5 子组件监听父组件传入值的变化方法

import {Component,Input,OnChanges,SimpleChanges} from '@angular/core';import {NavController} from 'ionic-angular'; @Component({selector: 'cs-img-lazy',templateUrl: 'cs-img-lazy.html'})export class CsImgLazyComponent implements OnChanges { @Input() default: string; @Input() src: string  constructor(public navCtrl: NavController) { } ngOnInit() {} ngOnChanges(changes: SimpleChanges) { console.log('ngOnChanges', this.src); this.loadImage(this.src, () => {  this.default = this.src; });} loadImage(url, callback) {var img = new Image();img.onload = () => {if (img.complete) {img.onload = nullcallback(img);return;}}img.src = url;}}