我如何检测模板中的 Prop 变化, Angular 是这样的:
但我不知道如何在模板中。
import { Component, Input, OnInit } from '@angular/core';
@Component({
selector: 'my-name',
template: `
<h2>First name: {{name}} ({{_name}})</h2>
`,
})
export class ChildComponent implements OnInit {
private _name: string;
constructor() {}
get name(): string {
// transform value for display
return this._name.toUpperCase();
}
@Input()
set name(name: string) {
console.log('prev value: ', this._name);
console.log('got name: ', name);
this._name = name;
}
ngOnInit() {
console.log('on init');
console.log(this._name);
}
}
我需要检测属性变化
最佳答案
您可以在属性更改时触发的方法上使用 @Watch
装饰器。
@Watch('name')
onNameChanged(newValue: string, oldValue: string) {
this._name = newValue;
}
Note on
@Watch
: this decorator only trigger on prop changed, it means theonNameChanged()
method won't be called the first time that prop is set. In order to intercept the first set, you have to use thecomponentWillLoad()
hook.componentWillLoad(){ this.onNameChanged(this.name); }
工作示例:
import { Component, Prop, Watch } from '@stencil/core';
@Component({
tag: 'my-name'
})
export class ChildComponent {
private _name: string;
@Prop() name: string = '';
@Watch('name')
onNameChanged(name: string) {
console.log('prev value: ', this._name);
console.log('got name: ', name);
this._name = name.toUpperCase();
}
componentWillLoad(){
this.onNameChanged(this.name);
}
render() {
return (<h2>First name: {this.name} ({this._name})</h2>);
}
}
关于angular - 模板更改@Prop() 检测,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/52976750/