In-depth Guides
Angular Aria

Multiselect

Overview

The multiselect pattern combines a read-only combobox trigger with a multi-select listbox popup to create highly accessible multiple-selection dropdowns with keyboard navigation and screen reader support.

Usage

The multiselect pattern works best when users need to choose multiple related items from a familiar set of options.

Consider using this pattern when:

  • Users need multiple selections - Tags, categories, filters, or labels where multiple choices apply
  • The option list is fixed (fewer than 20 items) - Users can scan options without search
  • Filtering content - Multiple criteria can be active simultaneously
  • Assigning attributes - Labels, permissions, or features where multiple values make sense
  • Related choices - Options that logically work together (such as selecting multiple team members)

Avoid this pattern when:

  • Only single selection is needed - Use the Select pattern for simpler single-choice dropdowns
  • The list has more than 20 items with search needed - Use the Autocomplete pattern with multiselect capability
  • Most or all options will be selected - A checklist pattern provides better visibility
  • Choices are independent binary options - Individual checkboxes communicate the choices more clearly

Features

The multiselect pattern combines Combobox and Listbox directives to provide a fully accessible dropdown with:

  • Keyboard Navigation - Navigate options with arrow keys, toggle with Space, close with Escape
  • Screen Reader Support - Built-in ARIA attributes including aria-multiselectable
  • Selection Count Display - Shows compact "Item + 2 more" pattern for multiple selections
  • Signal-Based Reactivity - Reactive state management using Angular signals
  • Smart Positioning - CDK Overlay handles viewport edges and scrolling
  • Persistent Selection - Selected options remain visible with checkmarks after selection

Examples

Basic multiselect

Users need to select multiple items from a list of options. A readonly combobox paired with a multi-enabled listbox provides familiar multiselect functionality with full accessibility support.

The multi attribute on ngListbox enables multiple selection. Press Space to toggle options, and the popup remains open for additional selections. The display shows the first selected item plus a count of remaining selections.

Multiselect with custom display

Options often need visual indicators like icons or colors to help users identify choices. Custom templates within options allow rich formatting while the display value shows a compact summary.

Each option displays an icon alongside its label. The display value updates to show the first selection's icon and text, followed by a count of additional selections. Selected options show a checkmark for clear visual feedback.

Controlled selection

Forms sometimes need to limit the number of selections or validate user choices. Programmatic control over selection enables these constraints while maintaining accessibility.

This example limits selections to two items. When the limit is reached, unselected options are disabled to prevent further selections, and the combobox display updates to reflect the choices.

Testing

The multiselect pattern can be tested using a combination of ComboboxHarness and ListboxHarness from @angular/aria/combobox/testing and @angular/aria/listbox/testing. Here is an example of how to use the harnesses to test a multiselect component:

import {ComponentFixture, TestBed} from '@angular/core/testing';
import {HarnessLoader} from '@angular/cdk/testing';
import {TestbedHarnessEnvironment} from '@angular/cdk/testing/testbed';
import {ComboboxHarness} from '@angular/aria/combobox/testing';
import {ListboxHarness} from '@angular/aria/listbox/testing';
import {MyMultiselectComponent} from './my-multiselect'; // Your component

describe('MyMultiselectComponent', () => {
  let fixture: ComponentFixture<MyMultiselectComponent>;
  let loader: HarnessLoader;

  beforeEach(async () => {
    TestBed.configureTestingModule({
      imports: [MyMultiselectComponent],
    });

    fixture = TestBed.createComponent(MyMultiselectComponent);
    await fixture.whenStable();
    loader = TestbedHarnessEnvironment.loader(fixture);
  });

  it('should allow selecting multiple options', async () => {
    const select = await loader.getHarness(ComboboxHarness);

    // Open the dropdown
    await select.open();

    // Get the listbox harness from the popup
    const listbox = await select.getPopupWidget(ListboxHarness);
    expect(await listbox.isMulti()).toBe(true);

    const options = await listbox.getOptions();

    // Select first and second options
    await options[0].click();
    await options[1].click();

    // Verify both options are selected
    expect(await options[0].isSelected()).toBe(true);
    expect(await options[1].isSelected()).toBe(true);

    // Close the dropdown
    await select.close();

    // Verify value is updated (e.g., comma separated list or count)
    expect(await (await select.host()).text()).toContain('Option 1, Option 2');
  });
});

API reference

For detailed API documentation, inspect the following API references: