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Getting started in EJ2 TypeScript Combo box control

10 Feb 202613 minutes to read

This section explains how to create a simple ComboBox component and configure its available functionalities in TypeScript, using Essential® JS 2 quickstart seed repository.

This application is integrated with the webpack.config.js configuration and uses the latest version of the webpack-cli. It requires Node.js v14.0 or higher. For more information about webpack and its features, refer to the webpack documentation.

Dependencies

The following list of dependencies are required to use the ComboBox component in your application.

|-- @syncfusion/ej2-dropdowns
    |-- @syncfusion/ej2-base
    |-- @syncfusion/ej2-data
    |-- @syncfusion/ej2-lists
    |-- @syncfusion/ej2-inputs
    |-- @syncfusion/ej2-navigations
    |-- @syncfusion/ej2-notifications
    |-- @syncfusion/ej2-popups
        |-- @syncfusion/ej2-buttons

Setup development environment

Open the command prompt from the required directory, and run the following command to clone the Syncfusion® JavaScript (Essential® JS 2) quickstart project from GitHub.

git clone https://github.com/SyncfusionExamples/ej2-quickstart-webpack- ej2-quickstart

After cloning the application in the ej2-quickstart folder, run the following command line to navigate to the ej2-quickstart folder.

cd ej2-quickstart

Add Syncfusion® JavaScript packages

Syncfusion® JavaScript (Essential® JS 2) packages are available on the npmjs.com public registry. You can install all Syncfusion® JavaScript (Essential® JS 2) controls in a single @syncfusion/ej2 package or individual packages for each control.

The quickstart application is preconfigured with the dependent @syncfusion/ej2 package in the ~/package.json file. Use the following command to install the dependent npm packages from the command prompt.

npm install

Import the Syncfusion® CSS styles

Syncfusion® JavaScript controls come with built-in themes, which are available in the installed packages. It’s easy to adapt the Syncfusion® JavaScript controls to match the style of your application by referring to one of the built-in themes.

The quickstart application is preconfigured to use the Material theme in the ~/src/styles/styles.css file, as shown below:

@import '../../node_modules/@syncfusion/ej2-base/styles/material.css';
@import '../../node_modules/@syncfusion/ej2-buttons/styles/material.css';
@import '../../node_modules/@syncfusion/ej2-inputs/styles/material.css';
@import '../../node_modules/@syncfusion/ej2-popups/styles/material.css';
@import '../../node_modules/@syncfusion/ej2-lists/styles/material.css';
@import '../../node_modules/@syncfusion/ej2-dropdowns/styles/material.css';

You can check out the themes section to know more about built-in themes and CSS reference for individual controls.

Initialize the ComboBox

The ComboBox can be initialized through three different tags which described in Initialize Tags.

Add the HTML input element that needs to be initialized as ComboBox in index.html.

[src/index.html]

<!DOCTYPE html>
<html lang="en">

<head>
    <title>Essential JS 2 ComboBox component</title>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=no" />
    <meta name="description" content="Essential JS 2" />
    <meta name="author" content="Syncfusion" />
    <link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet" />
</head>

<body>
    <div id='container' style="margin:0 auto; width:300px;">
        <!--element which is going to render the ComboBox-->
        <input type="text" tabindex="1" id='comboelement' />
    </div>

</body>

</html>

Now, import the ComboBox component to your app.ts and initialize it to the element #combo as shown below.

[src/app/app.ts]

import { ComboBox } from '@syncfusion/ej2-dropdowns';

// initialize ComboBox component
let comboBoxObject: ComboBox = new ComboBox();

// render initialized ComboBox
comboBoxObject.appendTo('#combo');

Binding data source

After initialization, populate the ComboBox with data using the dataSource property. Here, an array of string values is passed to the ComboBox component.

import { ComboBox } from '@syncfusion/ej2-dropdowns';

// define the array of data
let sportsData: string[] = ['Badminton', 'Cricket', 'Football', 'Golf', 'Tennis'];

// initialize ComboBox component
let comboBoxObject: ComboBox = new ComboBox({
    //set the data to dataSource property
    dataSource: sportsData
});

// render initialized ComboBox
comboBoxObject.appendTo('#comboelement');

Run the application

After completing the configuration required to render a basic ComboBox, run the following command to display the output in your default browser.

npm run start

The following example illustrates the output in your browser.

import { ComboBox } from '@syncfusion/ej2-dropdowns';

// defined the array of data
let sportsData: string[] = ['Badminton', 'Cricket', 'Football', 'Golf', 'Tennis'];

// initialize ComboBox component
let comboBoxObject: ComboBox = new ComboBox({
    //set the data to dataSource property
    dataSource: sportsData,
    // set placeholder to ComboBox input element
    placeholder: "Select a game"
});

// render initialized ComboBox
comboBoxObject.appendTo('#comboelement');
<!DOCTYPE html>
<html lang="en">

<head>
    <title>EJ2 ComboBox</title>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta name="description" content="Typescript UI Controls" />
    <meta name="author" content="Syncfusion" />
    <link href="styles.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/32.2.3/ej2-base/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/32.2.3/ej2-inputs/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/32.2.3/ej2-dropdowns/styles/material.css" rel="stylesheet" />
    <script src="https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.19.38/system.js"></script>
    <script src="systemjs.config.js"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>

<body>
    <div id='loader'>LOADING....</div>
    <div id='container' style="margin:50px auto 0; width:250px;">
        <br>
        <input type="text" tabindex="1" id='comboelement' />
    </div>
</body>

</html>

Custom values

The ComboBox allows users to enter custom values that are not in the predefined set. By default, this is enabled through the allowCustom property. In this case, both text and value fields are treated as the same. Custom values are sent to the post-back handler when a form is submitted.

import { ComboBox } from '@syncfusion/ej2-dropdowns';

// defined the array of data
let sportsData: { [key: string]: Object }[] = [
    { Id: 'game1', Game: 'Badminton' },
    { Id: 'game2', Game: 'Football' },
    { Id: 'game3', Game: 'Tennis' }
];

// initialize ComboBox component
let comboBoxObject: ComboBox = new ComboBox({
    //set the data to dataSource property
    dataSource: sportsData,
    // By default, its enabled. For your better understanding, showcase this property here.
    allowCustom: true,
    // maps the appropriate column to fields property
    fields: { text: 'Game', value: 'Id' },
    // set placeholder to ComboBox input element
    placeholder: "Select a game"
});

// render initialized ComboBox
comboBoxObject.appendTo('#comboelement');
<!DOCTYPE html>
<html lang="en">

<head>
    <title>EJ2 ComboBox</title>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta name="description" content="Typescript UI Controls" />
    <meta name="author" content="Syncfusion" />
    <link href="styles.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/32.2.3/ej2-base/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/32.2.3/ej2-inputs/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/32.2.3/ej2-dropdowns/styles/material.css" rel="stylesheet" />
    <script src="https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.19.38/system.js"></script>
    <script src="systemjs.config.js"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>

<body>
    <div id='loader'>LOADING....</div>
    <div id='container' style="margin:50px auto 0; width:250px;">
        <br>
        <input type="text" tabindex="1" id='comboelement' />
    </div>
</body>

</html>

Configure the popup list

By default, the width of the popup list automatically adjusts according to the ComboBox input element’s width, and the height of the popup list is 300px.

The height and width of the popup list can also be customized using the popupHeight and popupWidth properties, respectively.

In the following sample, popup list’s width and height are configured.

import { ComboBox } from '@syncfusion/ej2-dropdowns';

// define the array of data
let sportsData: string[] = ['Badminton', 'Cricket', 'Football', 'Golf', 'Tennis'];

// initialize ComboBox component
let comboBoxObject: ComboBox = new ComboBox({
    //set the data to dataSource property
    dataSource: sportsData,
    //set height to popup list
    popupHeight: '200px',
    //set width to popup list
    popupWidth: '250px',
    // set placeholder to ComboBox input element
    placeholder: "Select a game"
});

// render initialized ComboBox
comboBoxObject.appendTo('#comboelement');
<!DOCTYPE html>
<html lang="en">

<head>
    <title>EJ2 ComboBox</title>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta name="description" content="Typescript UI Controls" />
    <meta name="author" content="Syncfusion" />
    <link href="styles.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/32.2.3/ej2-base/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/32.2.3/ej2-inputs/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/32.2.3/ej2-dropdowns/styles/material.css" rel="stylesheet" />
    <script src="https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.19.38/system.js"></script>
    <script src="systemjs.config.js"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>

<body>
    <div id='loader'>LOADING....</div>
    <div id='container' style="margin:50px auto 0; width:250px;">
        <br>
        <input type="text" tabindex="1" id='comboelement' />
    </div>
</body>

</html>

See Also