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debounce rxjs typescript angular

0

Kamil KieÅczewski · 技术社区 · 7 年前

<div class="btn-plus" (click)="add(1)"> - </div>
<div class="txt"> {{ myValue }} </div>
<div class="btn-minus" (click)="add(-1)"> + </div>

在我的component.ts文件中,我有:

add(num) {
    this.myValue +=num;
    this.update(); // async function which will send PUT request
}

这个 this.update() 函数puts myValue 在大型JSON对象的适当字段中,并将其发送到服务器。

:当用户在短时间内点击按钮加减10倍时,请求将被发送10次。但我只想发送一次请求-上次单击后0.5秒。 怎么做 ?

2 回复 | 直到 6 年前

1

4

user4676340 user4676340 7 年前

使用 takeUntil 操作员:

export class AppComponent  {
  name = 'Angular';

  calls = new Subject();

  service = {
    getData: () => of({ id: 1 }).pipe(delay(500)),
  };

  click() {
    this.calls.next(true);
    this.service.getData().pipe(
      takeUntil(this.calls),
    ).subscribe(res => console.log(res));
  }
}

Stackblitz

2

Kamil KieÅczewski 7 年前

这是我在互联网上找到的部分答案,但我愿意接受更好的解决方案(或改进到下面的解决方案(指令)):

我在网上找到的 appDebounceClick

我移除 update 从 add 在.ts文件中:

add(num) {
    this.myValue +=num;
}

并按以下方式更改模板:

<div 
    appDebounceClick 
    (debounceClick)="update()" 
    (click)="add(1)" 
    class="btn-plus"
    > - 
</div>
<div class="txt"> {{ myValue }} </div>
<!-- similar for btn-minus -->

指令作者 Cory Rylan (我把代码放在这里,以防将来link停止工作):

import { Directive, EventEmitter, HostListener, Input, OnDestroy, OnInit, Output } from '@angular/core';
import { Subject } from 'rxjs/Subject';
import { Subscription } from 'rxjs/Subscription';
import { debounceTime } from 'rxjs/operators';

@Directive({
  selector: '[appDebounceClick]'
})
export class DebounceClickDirective implements OnInit, OnDestroy {
  @Input() debounceTime = 500;
  @Output() debounceClick = new EventEmitter();
  private clicks = new Subject();
  private subscription: Subscription;

  constructor() { }

  ngOnInit() {
    this.subscription = this.clicks.pipe(
      debounceTime(this.debounceTime)
    ).subscribe(e => this.debounceClick.emit(e));
  }

  ngOnDestroy() {
    this.subscription.unsubscribe();
  }

  @HostListener('click', ['$event'])
  clickEvent(event) {
    event.preventDefault();
    event.stopPropagation();
    this.clicks.next(event);
  }
}

3

1

Charly 6 年前

export const debounced = (cb, time) => {
  const db = new Subject();
  const sub = db.pipe(debounceTime(time)).subscribe(cb);
  const func = v => db.next(v);

  func.unsubscribe = () => sub.unsubscribe();

  return func;
};

一个例子是:

import { Component, OnInit } from '@angular/core';
import { debounced } from 'src/helpers';

@Component({
  selector: 'app-example',
  // Click calls `debouncedClick` instead of `myClick` directly
  template: '<button (click)="debouncedClick($event)">Click This</button>'
})
export class Example implements OnDestroy {
  debouncedClick; // Subject.next function

  constructor() {
    // Done in constructor or ngOnInit for `this` to resolve
    this.debouncedClick = debounced($event => this.myClick($event), 800);
  }

  // Called after debounced resolves (800ms from last call)
  myClick($event) {
    console.log($event);
  }

  ngOnDestroy() {
    // Stay clean!
    this.debouncedFunc.unsubscribe();
  }
}

也可以反转用法,在click上调用“myClick”,并使 debounced 回调执行所需的操作。经销商的选择。

(keyup) 事件也一样。

不确定是否真的需要取消订阅-实现起来比研究内存泄漏要快:)