标签:箭头函数 tac obs isp person lse get ssr ==
在 window-ref.ts 的实现里,定义了一个每隔 300 毫秒,通过 fromEvent 发射一个 resize event 的Observable:
/**
* Returns an observable for the window resize event and emits an event
* every 300ms in case of resizing. An event is simulated initially.
*
* If there‘s no window object available (i.e. in SSR), a null value is emitted.
*/
get resize$(): Observable<any> {
if (!this.nativeWindow) {
return of(null);
} else {
return fromEvent(this.nativeWindow, ‘resize‘).pipe(
debounceTime(300),
startWith({ target: this.nativeWindow }),
distinctUntilChanged()
);
}
}
加上 distingctUntilChanged 操作符后,能过滤掉完全一致的 resize event. 下面的例子,展示了如何使用 distingctUntilChanged,将数字序列里重复的数字过滤掉。distingctUntilChanged 默认会将当前元素和前一元素做比较。
import { of } from ‘rxjs‘;
import { distinctUntilChanged } from ‘rxjs/operators‘;
of(1, 1, 2, 2, 2, 1, 1, 2, 3, 3, 4).pipe(
distinctUntilChanged(),
)
.subscribe(x => console.log(x)); // 1, 2, 1, 2, 3, 4
下列例子展示了如何将自定义的比较逻辑,通过箭头函数作为参数,传入 distinctUntilChanged 里。
import { of } from ‘rxjs‘;
import { distinctUntilChanged } from ‘rxjs/operators‘;
interface Person {
age: number,
name: string
}
of<Person>(
{ age: 4, name: ‘Foo‘},
{ age: 7, name: ‘Bar‘},
{ age: 5, name: ‘Foo‘},
{ age: 6, name: ‘Foo‘},
).pipe(
distinctUntilChanged((p: Person, q: Person) => p.name === q.name),
)
.subscribe(x => console.log(x));
// displays:
// { age: 4, name: ‘Foo‘ }
// { age: 7, name: ‘Bar‘ }
// { age: 5, name: ‘Foo‘ }
Rxjs debounce 操作符在 SAP Spartacus 函数节流中的一个实际使用例子
标签:箭头函数 tac obs isp person lse get ssr ==
原文地址:https://www.cnblogs.com/sap-jerry/p/14671269.html