Expansion Panel

<mat-expansion-panel> provides an expandable details-summary view.

link Expansion-panel content

Each expansion-panel must include a header and may optionally include an action bar.

link Header

The <mat-expansion-panel-header> shows a summary of the panel content and acts as the control for expanding and collapsing. This header may optionally contain an <mat-panel-title> and an <mat-panel-description>, which format the content of the header to align with Material Design specifications.

By default, the expansion-panel header includes a toggle icon at the end of the header to indicate the expansion state. This icon can be hidden via the hideToggle property.

<mat-expansion-panel>
  <mat-expansion-panel-header>
    <mat-panel-title>
      This is the expansion title
    </mat-panel-title>
    <mat-panel-description>
      This is a summary of the content
    </mat-panel-description>
  </mat-expansion-panel-header>

  <p>This is the primary content of the panel.</p>

</mat-expansion-panel>

link Action bar

Actions may optionally be included at the bottom of the panel, visible only when the expansion is in its expanded state.

<mat-expansion-panel>
  <mat-expansion-panel-header>
    This is the expansion title
  </mat-expansion-panel-header>

  <p>This is the primary content of the panel.</p>

  <mat-action-row>
    <button mat-button>Click me</button>
  </mat-action-row>
</mat-expansion-panel>

link Disabling a panel

Expansion panels can be disabled using the disabled attribute. A disabled expansion panel can't be toggled by the user, but can still be manipulated programmatically.

<mat-expansion-panel [disabled]="isDisabled">
  <mat-expansion-panel-header>
    This is the expansion title
  </mat-expansion-panel-header>
  <mat-panel-description>
    This is a summary of the content
  </mat-panel-description>
</mat-expansion-panel>

link Accordion

Multiple expansion-panels can be combined into an accordion. The multi="true" input allows the expansions state to be set independently of each other. When multi="false" (default) just one panel can be expanded at a given time:

<mat-accordion>

  <mat-expansion-panel>
    <mat-expansion-panel-header>
      This is the expansion 1 title
    </mat-expansion-panel-header>

    This the expansion 1 content

  </mat-expansion-panel>

  <mat-expansion-panel>
    <mat-expansion-panel-header>
      This is the expansion 2 title
    </mat-expansion-panel-header>

    This the expansion 2 content

  </mat-expansion-panel>

</mat-accordion>

link Lazy rendering

By default, the expansion panel content will be initialized even when the panel is closed. To instead defer initialization until the panel is open, the content should be provided as an ng-template:

<mat-expansion-panel>
  <mat-expansion-panel-header>
    This is the expansion title
  </mat-expansion-panel-header>

  <ng-template matExpansionPanelContent>
    Some deferred content
  </ng-template>
</mat-expansion-panel>

link Accessibility

The expansion-panel aims to mimic the experience of the native <details> and <summary> elements. The expansion panel header has role="button" and also the attribute aria-controls with the expansion panel's id as value.

The expansion panel headers are buttons. Users can use the keyboard to activate the expansion panel header to switch between expanded state and collapsed state. Because the header acts as a button, additional interactive elements should not be put inside of the header.