beginUpdate()
Postpones rendering that can negatively affect performance until the endUpdate() method is called.
The beginUpdate() and endUpdate() methods reduce the number of renders in cases where extra rendering can negatively affect performance.
See Also
defaultOptions(rule)
Name | Type | Description |
---|---|---|
device | | |
Device parameters. |
options |
Options to be applied. |
defaultOptions is a static method that the UI component class supports. The following code demonstrates how to specify default properties for all instances of the DropDownBox UI component in an application executed on the desktop.
jQuery
DevExpress.ui.dxDropDownBox.defaultOptions({ device: { deviceType: "desktop" }, options: { // Here go the DropDownBox properties } });
Angular
import DropDownBox, { Properties } from "devextreme/ui/drop_down_box"; // ... export class AppComponent { constructor () { DropDownBox.defaultOptions<Properties>({ device: { deviceType: "desktop" }, options: { // Here go the DropDownBox properties } }); } }
Vue
<template> <div> <DxDropDownBox id="dropDownBox1" /> <DxDropDownBox id="dropDownBox2" /> </div> </template> <script> import DxDropDownBox from "devextreme-vue/drop-down-box"; import DropDownBox from "devextreme/ui/drop_down_box"; DropDownBox.defaultOptions({ device: { deviceType: "desktop" }, options: { // Here go the DropDownBox properties } }); export default { components: { DxDropDownBox } } </script>
React
import dxDropDownBox from "devextreme/ui/drop_down_box"; import DropDownBox from "devextreme-react/drop-down-box"; dxDropDownBox.defaultOptions({ device: { deviceType: "desktop" }, options: { // Here go the DropDownBox properties } }); export default function App() { return ( <div> <DropDownBox id="dropDownBox1" /> <DropDownBox id="dropDownBox2" /> </div> ) }
You can also set rules for multiple device types:
jQuery
const devicesConfig = [ { deviceType: 'desktop' }, { deviceType: 'tablet' }, { deviceType: 'phone' }, ]; devicesConfig.forEach(deviceConfig => { DevExpress.ui.dxDropDownBox.defaultOptions({ device: deviceConfig, options: { // Here go the DropDownBox properties } }); });
Angular
import DropDownBox, { Properties } from "devextreme/ui/drop_down_box"; // ... export class AppComponent { constructor () { const devicesConfig = [ { deviceType: 'desktop' }, { deviceType: 'tablet' }, { deviceType: 'phone' }, ]; devicesConfig.forEach(deviceConfig => { DropDownBox.defaultOptions<Properties>({ device: deviceConfig, options: { // Here go the DropDownBox properties } }); }); } }
Vue
<template> <div> <DxDropDownBox /> </div> </template> <script> import DxDropDownBox from "devextreme-vue/drop-down-box"; import DropDownBox from "devextreme/ui/drop_down_box"; const devicesConfig = [ { deviceType: 'desktop' }, { deviceType: 'tablet' }, { deviceType: 'phone' }, ]; devicesConfig.forEach(deviceConfig => { DropDownBox.defaultOptions({ device: deviceConfig, options: { // Here go the DropDownBox properties } }); }); export default { components: { DxDropDownBox } } </script>
React
import dxDropDownBox from "devextreme/ui/drop_down_box"; import DropDownBox from "devextreme-react/drop-down-box"; const devicesConfig = [ { deviceType: 'desktop' }, { deviceType: 'tablet' }, { deviceType: 'phone' }, ]; devicesConfig.forEach(deviceConfig => { dxDropDownBox.defaultOptions({ device: deviceConfig, options: { // Here go the DropDownBox properties } }); }); export default function App() { return ( <div> <DropDownBox /> </div> ) }
dispose()
jQuery
After calling this method, remove the DOM element associated with the UI component:
$("#myDropDownBox").dxDropDownBox("dispose"); $("#myDropDownBox").remove();
Angular
Use conditional rendering instead of this method:
<dx-drop-down-box ... *ngIf="condition"> </dx-drop-down-box>
Vue
Use conditional rendering instead of this method:
<template> <DxDropDownBox ... v-if="condition"> </DxDropDownBox> </template> <script> import DxDropDownBox from 'devextreme-vue/drop-down-box'; export default { components: { DxDropDownBox } } </script>
React
Use conditional rendering instead of this method:
import React from 'react'; import DropDownBox from 'devextreme-react/drop-down-box'; function DxDropDownBox(props) { if (!props.shouldRender) { return null; } return ( <DropDownBox ... > </DropDownBox> ); } class App extends React.Component { render() { return ( <DxDropDownBox shouldRender="condition" /> ); } } export default App;
endUpdate()
Refreshes the UI component after a call of the beginUpdate() method.
The beginUpdate() and endUpdate() methods reduce the number of renders in cases where extra rendering can negatively affect performance.
See Also
getButton(name)
Gets an instance of a custom action button.
Use the returned button instance to call the Button UI component's methods, for example, focus():
jQuery
const myCustomButton = $("#dropDownBoxContainer").dxDropDownBox("getButton", "myCustomButton"); myCustomButton.focus();
Angular
import { Component, ViewChild } from '@angular/core'; import { DxDropDownBoxComponent } from 'devextreme-angular'; @Component({ selector: 'app-root', templateUrl: './app.component.html', styleUrls: ['./app.component.css'] }) export class AppComponent { @ViewChild('dropDownBoxRef', { static: false }) dropDownBox: DxDropDownBoxComponent; // Prior to Angular 8 // @ViewChild('dropDownBoxRef') dropDownBox: DxDropDownBoxComponent; setFocus() { this.dropDownBox.instance.getButton('myCustomButton').focus(); } }
<dx-drop-down-box #dropDownBoxRef ... > </dx-drop-down-box>
Vue
<template> <DxDropDownBox ... :ref="dropDownBoxRef"> </DxDropDownBox> </template> <script> import 'devextreme/dist/css/dx.light.css'; import DxDropDownBox from 'devextreme-vue/drop-down-box'; export default { components: { DxDropDownBox }, data() { return { dropDownBoxRef } }, methods: { setFocus() { this.dropDownBox.getButton('myCustomButton').focus(); } }, computed: { dropDownBox: function() { return this.$refs[dropDownBoxRef].instance; } } } </script>
React
import React from 'react'; import 'devextreme/dist/css/dx.light.css'; import DropDownBox from 'devextreme-react/drop-down-box'; class App extends React.Component { constructor(props) { super(props); this.dropDownBoxRef = React.createRef(); this.setFocus = () => { this.dropDownBox.getButton('myCustomButton').focus(); }; } get dropDownBox() { return this.dropDownBoxRef.current.instance(); } render() { return ( <DropDownBox ... ref={this.dropDownBoxRef}> </DropDownBox> ); } } export default App;
getDataSource()
Gets the DataSource instance.
See Also
getInstance(element)
getInstance is a static method that the UI component class supports. The following code demonstrates how to get the DropDownBox instance found in an element with the myDropDownBox
ID:
// Modular approach import DropDownBox from "devextreme/ui/drop_down_box"; ... let element = document.getElementById("myDropDownBox"); let instance = DropDownBox.getInstance(element) as DropDownBox; // Non-modular approach let element = document.getElementById("myDropDownBox"); let instance = DevExpress.ui.dxDropDownBox.getInstance(element);
See Also
on(eventName, eventHandler)
Use this method to subscribe to one of the events listed in the Events section.
See Also
on(events)
Use this method to subscribe to several events with one method call. Available events are listed in the Events section.
See Also
registerKeyHandler(key, handler)
A handler. Accepts the keydown event as the argument. It is a EventObject or a jQuery.Event when you use jQuery.
The key argument accepts one of the following values:
- "backspace"
- "tab"
- "enter"
- "escape"
- "pageUp"
- "pageDown"
- "end"
- "home"
- "leftArrow"
- "upArrow"
- "rightArrow"
- "downArrow"
- "del"
- "space"
- "F"
- "A"
- "asterisk"
- "minus"
A custom handler for a key cancels the default handler for this key.
See Also
repaint()
Renders the component again without reloading data. Use the method to update the component's markup and appearance dynamically.
The repaint()
method re-initializes the component with new settings, resetting its state and history.
See Also
- reload() in DataSource | List
- refresh() in DataGrid | TreeList
If you have technical questions, please create a support ticket in the DevExpress Support Center.