不能++增加一个变量

Question

好的。所以我试图创建一种机制来记录一首歌被播放了多少次。所以在视觉上，我点击了每首歌曲，但播放变量不会随着每次点击而增加。

这是打字稿：

plays: number = 0;

  addPlay(song){
    song.plays = 0;
    song.plays++;
  }

和 HTML:

<ul> <!-- Each song on the album -->
    <li class="song-block"
        *ngFor='let song of songsToDisplay'
        (click)="getSong(song)"
        (mouseenter)="song.thumbsVisible=true"
        (mouseleave)="song.thumbsVisible=false">
      <div class="song-card"
           (click)="addPlay(song)">
        <p *ngIf="!song.isPlaying"
            class="song-number">{{song.tracknumber}}</p>
        <i *ngIf="song.isPlaying" class="fa fa-play fa-lg"></i>
        <p class="song-name">{{song.name}}</p>
        <p class="song-length">{{song.length}}</p>
        <div class="thumbs"
             *ngIf="song.thumbsVisible"> <!-- Thumbs section -->
          <i class="fa fa-thumbs-up fa-lg" [ngClass]="selected"
             (click)="thumbs(song)"
             >
          </i>
          <i class="fa fa-thumbs-down fa-lg" [ngClass]="selected"
             (click)="thumbs(song)"
             >
          </i>
        </div>

        <p class="plays">{{song.plays}}</p> <---- PLAYS
        <svg class="explicit"
            *ngIf="albumToDisplay.isExplicit === 'true'"
            viewBox="0 0 24 24"
            preserveAspectRatio="xMidYMid meet"
            focusable="false">
              <g class="style-scope iron-icon">
                <path d="M19 3H5c-1.1 0-2 .9-2 2v14c0 1.1.9 2 2 2h14c1.1 0 2-.9 2-2V5c0-1.1-.9-2-2-2zm-4 6h-4v2h4v2h-4v2h4v2H9V7h6v2z"></path></g></svg>
      </div>
    </li>
  </ul>

Answer 1

您每次调用 addPlay 时都会将计数器重置为 0。所以变量确实在递增——但总是递增到 1.

song.plays = 0;

尝试删除该行。

如果 plays 没有在任何地方初始化，您可能需要用这样的东西替换上面的内容；

if (song.plays === undefined) {
    song.plays = 0;
}

不能++增加一个变量

Can't ++Increment a variable

javascript

increment

typescript

angular