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Getting started with JavaScript ComboBox control

17 Mar 2023 / 4 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.

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 of the development environment

To get you started with ComboBox component, you need to clone the Essential JS 2 quickstart project and install the packages by using the following commands.

git clone https://github.com/syncfusion/ej2-quickstart.git quickstart
cd quickstart
npm install

The project is preconfigured with common settings (src/styles/styles.css, system.config.js ) to start with all Essential JS 2 components.

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" />

    <!--style reference from app-->
    <link href="/styles/styles.css" rel="stylesheet" />

    <!--system js reference and configuration-->
    <script src="node_modules/systemjs/dist/system.src.js" type="text/javascript"></script>
    <script src="system.config.js" type="text/javascript"></script>
</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.

Source

Preview

app.ts

index.html

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="//cdn.syncfusion.com/ej2/20.4.48/ej2-base/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/20.4.48/ej2-inputs/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/20.4.48/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>
</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.

Source

Preview

app.ts

index.html

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="//cdn.syncfusion.com/ej2/20.4.48/ej2-base/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/20.4.48/ej2-inputs/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/20.4.48/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>
</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>

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.

Source

Preview

app.ts

index.html

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="//cdn.syncfusion.com/ej2/20.4.48/ej2-base/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/20.4.48/ej2-inputs/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/20.4.48/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>
</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>

Getting started with JavaScript ComboBox control

Dependencies

Set up of the development environment

Initialize the ComboBox

Binding data source

Run the application

Custom values

Configure the popup list

See Also