我正在使用Angular 2.
现在我有两个@input aa和bb.我想要做：
>如果aa发生变化,请做点什么.
>如果bb发生变化,请做其他事情.
如何知道ngOnChanges中哪些@Input更改？谢谢
@Input() aa;
@Input() bb;
ngOnChanges(changes: { [propName: string]: SimpleChange }) {
// if aa changes,do something
// if bb changes,do other thing
}
可能会这样做
ngOnChanges(changes: { [propName: string]: SimpleChange }) {
if( changes['aa'] && changes['aa'].prevIoUsValue != changes['aa'].currentValue ) {
// aa prop changed
}
if( changes['bb'] && changes['bb'].prevIoUsValue != changes['bb'].currentValue ) {
// bb prop changed
}
}
不过,我对未定义的属性进行定义感到惊讶.从食谱中,我预计只会定义更改的属性.
https://angular.io/docs/ts/latest/cookbook/component-communication.html#!#parent-to-child-on-changes
如果这太冗长,您也可以尝试使用setter方法：
_aa: string;
_bb: string;
@Input() set aa(value: string) {
this._aa = value;
// do something on 'aa' change
}
@Input() set bb(value: string) {
this._bb = value;
// do something on 'bb' change
}
https://angular.io/docs/ts/latest/cookbook/component-communication.html#!#parent-to-child-setter
