Web Components Componente de lista desplegable - Descripción general

    Rica en funciones, la lista desplegable de Web Components ofrece filtrado listo para usar, accesibilidad, valores preseleccionados, enlace de datos flexible, agrupación, personalización de la interfaz de usuario y más. Lo que este componente hace prácticamente es reemplazar de manera efectiva y fácil las etiquetas de selección HTML, lo que permite a los usuarios elegir rápidamente un valor no editable de un conjunto predefinido de varias opciones.

    El componente desplegable Ignite UI for Web Components muestra una lista de alternancia de valores predefinidos y permite a los usuarios seleccionar fácilmente un solo elemento de opción con un clic. Se puede configurar rápidamente para que actúe como un menú desplegable de Web Components o simplemente puede usarlo para brindar información visual más útil agrupando datos. Además, con la agrupación se pueden utilizar tanto datos planos como jerárquicos.

    Con nuestro componente, obtiene todas las funciones y opciones de personalización que necesita para su proyecto: personalizaciones de estilo, opciones de ubicación Web Components desplegable, plantillas y la capacidad de cambiar qué y cómo se muestra en el encabezado, pie de página, cuerpo, lista, etc.

    Web Components Dropdown Example

    El siguiente ejemplo de lista desplegable de Web Components muestra el uso de un menú desplegable de Web Components interactivo simple en acción con tres opciones básicas para elegir. Vea cómo funciona.

    How to use the Dropdown List with Ignite UI for Web Components

    En primer lugar, debe instalar el Ignite UI for Web Components ejecutando el siguiente comando:

    npm install igniteui-webcomponents

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

defineComponents(IgcDropdownComponent);

    Para una introducción completa al Ignite UI for Web Components, lee el tema Empezar.

    La forma más sencilla de empezar a usar elIgcDropdownComponent uso es la siguiente:

    <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 Web Components 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 IgcPositionStrategy of the Web Components 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 Web Components 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 Web Components Dropdown list to its target can be specified using the distance property.

    Selección

    The IgcDropdownComponent emits the Change 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 Web Components Dropdown's items can also be grouped using the IgcDropdownGroupComponent, making it easier for users to differentiate separate categories. See it in action in this Web Components Dropdown List example:

    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.

    igc-dropdown::part(list) {
  height: 220px;
}

igc-dropdown-item[selected] {
  background: var(--ig-success-300);
}

igc-dropdown-group::part(label) {
  display: flex;
  justify-content: center;
}

    API Reference

    Additional Resources