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Getting started with JavaScript Dropdown Tree control

20 Oct 2021 / 4 minutes to read

This section explains you about how to create a simple Dropdown Tree control and configure its available functionalities in TypeScript using the Essential JS 2 quickstart.

Dependencies

The following list of dependencies are required to use the Dropdown Tree control in your application.

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

Set up of the development environment

To get started with the Dropdown Tree control, you have to clone the Essential JS 2 quickstart project and install the npm packages by using the following commands.

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

The project is pre-configured with the common settings (src/styles/styles.css, system.config.js ) to start all the Essential JS 2 controls.

Initialize the Dropdown Tree

Add the HTML input element that needs to be initialized as a Dropdown Tree in index.html.

[src/index.html]

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

<head>
    <title>Essential JS 2 Dropdown Tree control</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 Dropdown Tree-->
        <input type="text" tabindex="1" id='ddltreeelement' />
    </div>

</body>

</html>

Now, import the Dropdown Tree control to your app.ts and initialize it to the element #ddltreeelement as shown below.

[src/app/app.ts]

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

// initialize Dropdown Tree control
let DropDownTreeObject: DropDownTree = new DropDownTree();

// render initialized Dropdown Tree
DropDownTreeObject.appendTo('#ddltreeelement');

Binding data source

The Dropdown Tree control can load the data either from local data sources or remote data services. This can be done using the dataSource property that is a member of the fields property. The dataSource property supports array of JavaScript objects and DataManager. Here, an array of JSON values is passed to the Dropdown Tree control.

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

//define the array of JSON
let data: { [key: string]: Object }[] = [
    {
        nodeId: '01', nodeText: 'Music',
        nodeChild: [
            { nodeId: '01-01', nodeText: 'Gouttes.mp3' }
        ]
    },
    {
        nodeId: '02', nodeText: 'Videos', expanded: true,
        nodeChild: [
            { nodeId: '02-01', nodeText: 'Naturals.mp4' },
            { nodeId: '02-02', nodeText: 'Wild.mpeg' },
        ]
    },
    {
        nodeId: '03', nodeText: 'Documents',
        nodeChild: [
            { nodeId: '03-01', nodeText: 'Environment Pollution.docx' },
            { nodeId: '03-02', nodeText: 'Global Water, Sanitation, & Hygiene.docx' },
            { nodeId: '03-03', nodeText: 'Global Warming.ppt' },
            { nodeId: '03-04', nodeText: 'Social Network.pdf' },
            { nodeId: '03-05', nodeText: 'Youth Empowerment.pdf' },
        ]
    },
];

// initialize Dropdown Tree control
let DropDownTreeObject: DropDownTree = new DropDownTree({
    //binding data source through fields property
    fields: { dataSource: data, value: 'nodeId', text: 'nodeText', child: 'nodeChild' }
});

// render initialized Dropdown Tree
DropDownTreeObject.appendTo('#ddltreeelement');

Run the application

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

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npm run start

The following example explains the output in your browser.

Source
Preview
app.ts
index.html
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import { DropDownTree } from '@syncfusion/ej2-dropdowns';

//define the array of JSON
let data: { [key: string]: Object }[] = [
    {
        nodeId: '01', nodeText: 'Music',
        nodeChild: [
            { nodeId: '01-01', nodeText: 'Gouttes.mp3' }
        ]
    },
    {
        nodeId: '02', nodeText: 'Videos', expanded: true,
        nodeChild: [
            { nodeId: '02-01', nodeText: 'Naturals.mp4' },
            { nodeId: '02-02', nodeText: 'Wild.mpeg' },
        ]
    },
    {
        nodeId: '03', nodeText: 'Documents',
        nodeChild: [
            { nodeId: '03-01', nodeText: 'Environment Pollution.docx' },
            { nodeId: '03-02', nodeText: 'Global Water, Sanitation, & Hygiene.docx' },
            { nodeId: '03-03', nodeText: 'Global Warming.ppt' },
            { nodeId: '03-04', nodeText: 'Social Network.pdf' },
            { nodeId: '03-05', nodeText: 'Youth Empowerment.pdf' },
        ]
    },
];

// initialize Dropdown Tree control
let DropDownTreeObject: DropDownTree = new DropDownTree({
    //binding data source through fields property
    fields: { dataSource: data, value: 'nodeId', text: 'nodeText', child: 'nodeChild' }
    // set placeholder to Dropdown Tree input element
    placeholder: "Select a Item"
});

// render initialized Dropdown Tree
DropDownTreeObject.appendTo('#ddltreeelement');
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<!DOCTYPE html>
<html lang="en">

<head>
    <title>Essential JS 2 DropDownList</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/ej2-base/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/ej2-inputs/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/ej2-buttons/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/ej2-lists/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/ej2-navigations/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/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:0 auto; width:250px;">
        <input type="text" tabindex="1" id='ddltreeelement' />
    </div>
</body>

</html>