Javascript/Angular 5 - 单击多个按钮只会影响一个

Question

我有一个由 4 个按钮组成的网格，一旦其中一个被单击，它将调用一个名为 doSearch 的函数，该函数检查单击了哪个按钮，并根据它为 last_search 分配一个字符串 值。

但是，当我单击四个按钮中的任何一个时，我似乎总是只按下 edm 按钮并向控制台读取“我是 edm”。

谁能解释一下这是为什么？

html

<!-- grid for music -->
<ng-container *ngIf="show" >
  <div class="mdl-grid">
    <div class="mdl-cell mdl-cell--1-col">
      <button mat-button id="edm-btn" type="submit" (click)="doSearch($event)">EDM</button>
    </div>
    <div class="mdl-cell mdl-cell--1-col">
      <button mat-button id="house-btn" type="submit" (click)="doSearch($event)">House</button>
    </div>
    <div class="mdl-cell mdl-cell--1-col">
      <button mat-button id="pop-btn" type="submit" (click)="doSearch($event)">Pop</button>
    </div>
    <div class="mdl-cell mdl-cell--1-col">
      <button mat-button id="dubstep-btn" type="submit" (click)="doSearch($event)">Dubstep</button>
    </div>
  </div>
</ng-container>

函数代码

doSearch(event): void {

    if (document.getElementById('edm-btn')) {
      this.last_search = 'edm';
      console.log('i am edm');
    } else if (document.getElementById('house-btn')) {
      this.last_search = 'house';
      console.log('i am house');
    } else if (document.getElementById('pop-btn')) {
      this.last_search = 'pop';
      console.log('i am pop');
    } else if (document.getElementById('dubstep-btn')) {
      this.last_search = 'dubstep';
      console.log('i am dubstep');
    }
}

---

修复:

我决定不传递按钮的id，而是直接传递一个字符串到doSearch的函数调用中

html

<!-- grid for music -->
<ng-container *ngIf="show" >
  <div class="mdl-grid">
    <div class="mdl-cell mdl-cell--1-col">
      <button mat-button id="edm-btn" type="submit" (click)="doSearch('edm')">EDM</button>
    </div>
    <div class="mdl-cell mdl-cell--1-col">
      <button mat-button id="house-btn" type="submit" (click)="doSearch('house')">House</button>
    </div>
    <div class="mdl-cell mdl-cell--1-col">
      <button mat-button id="pop-btn" type="submit" (click)="doSearch('pop')">Pop</button>
    </div>
    <div class="mdl-cell mdl-cell--1-col">
      <button mat-button id="dubstep-btn" type="submit" (click)="doSearch('dubstep')">Dubstep</button>
    </div>
  </div>
</ng-container>

函数

doSearch(category): void {

    console.log(JSON.stringify(category, null, 2));
    if (category === 'edm') {
      this.last_search = 'edm';
      console.log('i am edm');
    } else if (category === 'house') {
      this.last_search = 'house';
      console.log('i am house');
    } else if (category === 'pop') {
      this.last_search = 'pop';
      console.log('i am pop');
    } else if (category === 'dubstep') {
      this.last_search = 'dubstep';
      console.log('i am dubstep');
    }
}

Answer 1

这是因为无论您通过什么事件，您的第一个条件始终为真。您正在传递一个事件，而不是实际数据，并检查一个元素是否存在，即使它已经存在。