Web Components Dropdown Overview

    The Web Components Dropdown is a component, which displays a toggleable list of predefined values and allows users to easily select a single option item with a click. It can be quickly configured to act as a dropdown menu or you can simply use it to deliver more useful visual information by grouping data. With grouping you can use both flat and hierarchical data.

    Web Components Dropdown Example

    Usage

    First, you need to install the Ignite UI for Web Components by running the following command:

    npm install igniteui-webcomponents

    import {
    defineComponents,
    IgcDropdownComponent
} from "igniteui-webcomponents";
import 'igniteui-webcomponents/themes/light/bootstrap.css';

defineComponents(IgcDropdownComponent);

    The simplest way to start using the IgcDropdownComponent is as follows:

    <igc-dropdown>
    <igc-button slot="target">Options</igc-button>
    <igc-dropdown-item>Option 1</igc-dropdown-item>
    <igc-dropdown-item>Option 2</igc-dropdown-item>
    <igc-dropdown-item>Option 3</igc-dropdown-item>
</igc-dropdown>

    Target

    The Dropdown list is positioned relatively to its target. The target slot allows you to provide a built-in component which toggles the open property on click. In some cases you would want to use an external target or use another event to toggle the opening of the Dropdown. You can achieve this using the showTarget, hide and toggleTarget methods which allow you to provide the target as a parameter. By default, the Dropdown list uses absolute CSS position. You will need to set the positionStrategy of the Dropdown to fixed when the target element is inside a fixed container, but the Dropdown is not. The Dropdown list is automatically sized based on its content, if you want the list to have the same width as the target, you should set the sameWidth property to true.

    Position

    The preferred placement of the Dropdown can be set using the placement property. The default placement of the Dropdown is bottom-start. The flip property determines whether the placement should be flipped if there is not enough space to display the Dropdown at the specified placement. The distance from the Dropdown list to its target can be specified using the distance property.

    Selection

    The IgcDropdownComponent emits the igcChange event when the user selects an item. The select method of the Dropdown allows you to select an item by its index or value.

    Item

    The IgcDropdownItemComponent represents a selectable item in the Dropdown list. You could predefine a selected item by setting the selected property. You could also disable an item so that it can't be selected using the disabled property. The IgcDropdownItemComponent has a default slot which allows you to specify the content of the item. You could also provide custom content to be rendered before or after the content using the prefix and suffix slots. The value property allows you to provide a custom value to an item. If the value is not set, it resolves to the text content of the item.

    You could use the IgcDropdownHeaderComponent to provide a header for a group of items.

    Group

    The Dropdown items can also be grouped using the IgcDropdownGroupComponent, making it easier for users to differentiate separate categories.

    Scroll Strategy

    The scrollStrategy property determines the behavior of the component during scrolling the container of the target element. The default value is scroll which means that the Dropdown will be scrolled with its target. Setting the property to block will block the scrolling if the Dropdown is opened. You could also set the property to close which means that the Dropdown will be closed automatically on scroll.

    Keep Open

    By default, the Dropdown is closed automatically when the user clicks outside of it or selects an item. You could prevent this behavior using the keepOpenOnOutsideClick and keepOpenOnSelect properties.

    Styling

    You can change the appearance of the Dropdown and its items, by using the exposed CSS parts. The IgcDropdownComponent exposes base and list parts, the IgcDropdownItemComponent exposes prefix, content and suffix parts and the IgcDropdownGroupComponent exposes label part.

    API Reference

    Additional Resources