如何在angular中折叠和扩展？

ng add @angular/material

import { MatExpansionModule } from '@angular/material/expansion';

@NgModule({
  imports: [
    // ...
    MatExpansionModule
  ],
  // ...
})
export class YourModule { }

<mat-expansion-panel>
  <mat-expansion-panel-header>
    <mat-panel-title>
      折叠标题
    </mat-panel-title>
  </mat-expansion-panel-header>
  <p>折叠内容</p>
</mat-expansion-panel>

isExpanded = false;

<mat-expansion-panel [expanded]="isExpanded">
  <!-- ... -->
</mat-expansion-panel>

<button mat-button (click)="isExpanded = !isExpanded" [matExpansionToggle]="panel">
  切换展开/折叠
</button>
<mat-expansion-panel #panel>
  <!-- ... -->
</mat-expansion-panel>