Getting started in EJ2 TypeScript Combo box control

2 Feb 202412 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 v14.15.0 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-popups
        |-- @syncfusion/ej2-buttons

Set up 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

To render ComboBox component, need to import dropdowns and its dependent components styles as given below 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';

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 #comboelement 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('#comboelement');

Binding data source

After initializing, 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/ej2/25.1.35/ej2-base/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/25.1.35/ej2-inputs/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/25.1.35/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 the user to give input as custom value which is not required to present in predefined set of values. By default, this support is enabled by allowCustom property. In this case, both text field and value field considered as same.
The custom value will be sent to post back handler when a form is about to be 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/ej2/25.1.35/ej2-base/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/25.1.35/ej2-inputs/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/25.1.35/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 has ‘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/ej2/25.1.35/ej2-base/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/25.1.35/ej2-inputs/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/25.1.35/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