Angular mat-sidenav属性是Handset $ | 异步解释

Question

<mat-sidenav-container class="sidenav-container">
  <mat-sidenav #drawer class="sidenav" fixedInViewport="true" [attr.role]="(isHandset$ | async) ? 'dialog' : 'navigation'"
    [mode]="(isHandset$ | async) ? 'push' : 'push'" [opened]="!(isHandset$ | async)">
    <mat-toolbar color="primary">Menu</mat-toolbar>
    <mat-nav-list>
      <a mat-list-item href="#">Link 1</a>
      <a mat-list-item href="#">Link 2</a>
      <a mat-list-item href="#">Link 3</a>
    </mat-nav-list>
  </mat-sidenav>

我不明白代码中写的是什么,(isHandset$ | async)请解释一下

Answer 1

'手机'是角度材质布局的断点名称之一.断点名称列表是Handset,Tablet,Web,HandsetPortrait,TabletPortrait,WebPortrait,HandsetLandscape,TabletLandscape,WebLandscape.

有关材料布局断点的更多信息,请查看https://material.io/design/layout/responsive-layout-grid.html#breakpoints

在上面的示例中,isHandset $来自相应的组件.ts文件.请在组件文件中查找与下面类似的代码.

isHandset$: Observable<boolean> = this.breakpointObserver.observe(Breakpoints.Handset)
    .pipe(
      map(result => result.matches)
    );

当您调整浏览器大小并且浏览器宽度与手机(手机屏幕)匹配时,宽度isHandset $设置为true.!(isHandset $ | async)依次将sidenav抽屉的"已打开"属性设置为false并折叠sidenav抽屉.

因为isHandset $是一个Observable属性,所以'async'管道用于异步调用.