Getting started in EJ2 JavaScript Heatmap chart control

22 Nov 202324 minutes to read

The Essential JS 2 for JavaScript (global script) is an ES5 formatted pure JavaScript framework which can be directly used in latest web browsers.

control Initialization

The Essential JS 2 JavaScript controls can be initialized by using either of the following ways.

Using local script and style references in a HTML page.
Using CDN link for script and style reference.

Using local script and style references in a HTML page

Step 1: Create an app folder myapp for Essential JS 2 JavaScript controls.

Step 2: You can get the global scripts and styles from the Essential Studio JavaScript (Essential JS 2) build installed location.

Syntax:

Script: **(installed location)**/Syncfusion/Essential Studio/{RELEASE_VERSION}/Essential JS 2/{PACKAGE_NAME}/dist/global/{PACKAGE_NAME}.min.js

Example:

Script: C:/Program Files (x86)/Syncfusion/Essential Studio/16.2.45/Essential JS 2/ej2-heatmap/dist/global/ej2-heatmap.min.js

Step 3: Create a folder myapp/resources and copy/paste the dependent scripts and styles from the above installed location to myapp/resources location.

Step 4: Create a HTML page (index.html) in myapp location and add the Essentials JS 2 script and style references.

<!DOCTYPE html>
  <html xmlns="http://www.w3.org/1999/xhtml">
       <head>
            <title>Essential JS 2</title>
            <script src="resources/ej2-base.min.js" type="text/javascript"></script>
            <script src="resources/ej2-data.min.js" type="text/javascript"></script>
            <script src="resources/ej2-svg-base.min.js" type="text/javascript"></script>
            <script src="resources/ej2-heatmap.min.js" type="text/javascript"></script>
       </head>
       <body>
       </body>
  </html>

Step 5: Now, add the div element and initiate the Essential JS 2 Heatmap control in the index.html by using following code

<!DOCTYPE html>
  <html xmlns="http://www.w3.org/1999/xhtml">
       <head>
            <title>Essential JS 2</title>
            <script src="resources/ej2-base.min.js" type="text/javascript"></script>
            <script src="resources/ej2-data.min.js" type="text/javascript"></script>
            <script src="resources/ej2-svg-base.min.js" type="text/javascript"></script>
            <script src="resources/ej2-heatmap.min.js" type="text/javascript"></script>
       </head>
       <body>
            <!-- Add the HTML <div> element  -->
             <div id="container"></div>
            <script>
                // initialize heatmap control
                var heatmap = new ej.heatmap.HeatMap();

                // Render initialized heatmap.
                heatmap.appendTo('#container')
            </script>
       </body>
  </html>

Step 6: Now, run the index.html in web browser, it will render the Essential JS 2 HeatMap control.

Using CDN link for script and style reference

Step 1: Create an app folder quickstart for the Essential JS 2 JavaScript controls.

Step 2: The Essential JS 2 controls’ global scripts are already hosted in the below CDN link formats.

Common Control Script:

Syntax: https://cdn.syncfusion.com/ej2/{RELEASE_VERSION}/dist/ej2.min.js

Example:

Script: https://cdn.syncfusion.com/ej2/23.1.36/dist/ej2.min.js

Individual Control Scripts:

Syntax

http://cdn.syncfusion.com/ej2/{RELEASE_VERSION}/{PACKAGE_NAME}/dist/global/{PACKAGE_NAME}.min.js

Example:

HeatMap Script: https://cdn.syncfusion.com/ej2/23.1.36/ej2-heatmap/dist/global/ej2-heatmap.min.js

Dependency Scripts

https://cdn.syncfusion.com/ej2/23.1.36/ej2-base/dist/global/ej2-base.min.js

https://cdn.syncfusion.com/ej2/23.1.36/ej2-data/dist/global/ej2-data.min.js

https://cdn.syncfusion.com/ej2/23.1.36/ej2-svg-base/dist/global/ej2-svg-base.min.js

Step 3: Create a HTML page (index.html) in quickstart location and add the CDN link references. Now, add the div element and initiate the Essential JS 2 Heatmap control in the index.html by using following code.

index.html
<!DOCTYPE html><html xmlns="http://www.w3.org/1999/xhtml"><head>
            <title>Essential JS 2</title>
            <script src="http://cdn.syncfusion.com/ej2/ej2-base/dist/global/ej2-base.min.js" type="text/javascript"></script>
            <script src="http://cdn.syncfusion.com/ej2/ej2-data/dist/global/ej2-data.min.js" type="text/javascript"></script>
            <script src="http://cdn.syncfusion.com/ej2/ej2-svg-base/dist/global/ej2-svg-base.min.js" type="text/javascript"></script>
            <script src="http://cdn.syncfusion.com/ej2/ej2-heatmap/dist/global/ej2-heatmap.min.js" type="text/javascript"></script>
       <script src="https://cdn.syncfusion.com/ej2/28.1.33/dist/ej2.min.js" type="text/javascript"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>
       <body>
            <!-- Add the HTML <div> element  -->
            <div id="container"></div>
            <script>
                // initialize heatmap component
                var heatmap = new ej.heatmap.HeatMap();

                // Render initialized heatmap.
                heatmap.appendTo('#container')
            </script>
       
  <script>
var ele = document.getElementById('container');
if(ele) {
  ele.style.visibility = "visible";
}   
      </script>
<script src="index.js" type="text/javascript"></script>
</body></html>

Step 4: Now, run the index.html in web browser, it will render the Essential JS 2 HeatMap control.

Populate HeatMap with data

This section explains how to populate the following two-dimensional array data to the HeatMap.

index.js
index.html
var heatmapData = [
     [73, 39, 26, 39, 94, 0],
            [93, 58, 53, 38, 26, 68],
            [99, 28, 22, 4, 66, 90],
            [14, 26, 97, 69, 69, 3],
            [7, 46, 47, 47, 88, 6],
            [41, 55, 73, 23, 3, 79],
            [56, 69, 21, 86, 3, 33],
            [45, 7, 53, 81, 95, 79],
            [60, 77, 74, 68, 88, 51],
            [25, 25, 10, 12, 78, 14],
            [25, 56, 55, 58, 12, 82],
            [74, 33, 88, 23, 86, 59]];

var heatmap = new ej.heatmap.HeatMap({
     dataSource: heatmapData
}, '#element');
<!DOCTYPE html><html lang="en"><head>
    <title>EJ2 HeatMap</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="index.css" rel="stylesheet">
    
    
<script src="https://cdn.syncfusion.com/ej2/28.1.33/dist/ej2.min.js" type="text/javascript"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>

<body>
    
    <div id="container">
        <div id="element"></div>
    </div>


<script>
var ele = document.getElementById('container');
if(ele) {
  ele.style.visibility = "visible";
}   
      </script>
<script src="index.js" type="text/javascript"></script>
</body></html>

Enable axis labels

You can add axis labels to the HeatMap and format those labels using the xAxis and yAxis properties. Axis labels provide additional information about the data points populated in the HeatMap.

index.js
index.html
var heatmapData = [
     [73, 39, 26, 39, 94, 0],
     [93, 58, 53, 38, 26, 68],
     [99, 28, 22, 4, 66, 90],
     [14, 26, 97, 69, 69, 3],
     [7, 46, 47, 47, 88, 6],
     [41, 55, 73, 23, 3, 79],
     [56, 69, 21, 86, 3, 33],
     [45, 7, 53, 81, 95, 79],
     [60, 77, 74, 68, 88, 51],
     [25, 25, 10, 12, 78, 14],
     [25, 56, 55, 58, 12, 82],
     [74, 33, 88, 23, 86, 59]];

var heatmap = new ej.heatmap.HeatMap({
        xAxis: {
            labels: ['Nancy', 'Andrew', 'Janet', 'Margaret', 'Steven', 
                        'Michael', 'Robert', 'Laura', 'Anne', 'Paul', 'Karin',   'Mario'],
        },
        yAxis: {
            labels: ['Mon', 'Tues', 'Wed', 'Thurs', 'Fri', 'Sat'],
        },
     dataSource: heatmapData,   
}, '#element');
<!DOCTYPE html><html lang="en"><head>
    <title>EJ2 HeatMap</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="index.css" rel="stylesheet">
    
    
<script src="https://cdn.syncfusion.com/ej2/28.1.33/dist/ej2.min.js" type="text/javascript"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>

<body>
    
    <div id="container">
        <div id="element"></div>
    </div>


<script>
var ele = document.getElementById('container');
if(ele) {
  ele.style.visibility = "visible";
}   
      </script>
<script src="index.js" type="text/javascript"></script>
</body></html>

Add HeatMap title

Add a title using the titleSettings property to the HeatMap to provide quick information to the user about the data populated in the HeatMap.

index.js
index.html
var heatmapData = [
     [73, 39, 26, 39, 94, 0],
     [93, 58, 53, 38, 26, 68],
     [99, 28, 22, 4, 66, 90],
     [14, 26, 97, 69, 69, 3],
     [7, 46, 47, 47, 88, 6],
     [41, 55, 73, 23, 3, 79],
     [56, 69, 21, 86, 3, 33],
     [45, 7, 53, 81, 95, 79],
     [60, 77, 74, 68, 88, 51],
     [25, 25, 10, 12, 78, 14],
     [25, 56, 55, 58, 12, 82],
     [74, 33, 88, 23, 86, 59]];

var heatmap = new ej.heatmap.HeatMap({
     titleSettings: {
            text: 'Sales Revenue per Employee (in 1000 US$)',
            textStyle: {
                size: '15px',
                fontWeight: '500',
                fontStyle: 'Normal',
                fontFamily: 'Segoe UI'
            }
        },
        xAxis: {
            labels: ['Nancy', 'Andrew', 'Janet', 'Margaret', 'Steven', 
                        'Michael', 'Robert', 'Laura', 'Anne', 'Paul', 'Karin',   'Mario'],
        },
        yAxis: {
            labels: ['Mon', 'Tues', 'Wed', 'Thurs', 'Fri', 'Sat'],
        },
     dataSource: heatmapData,   
}, '#element');
<!DOCTYPE html><html lang="en"><head>
    <title>EJ2 HeatMap</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="index.css" rel="stylesheet">
    
    
<script src="https://cdn.syncfusion.com/ej2/28.1.33/dist/ej2.min.js" type="text/javascript"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>

<body>
    
    <div id="container">
        <div id="element"></div>
    </div>


<script>
var ele = document.getElementById('container');
if(ele) {
  ele.style.visibility = "visible";
}   
      </script>
<script src="index.js" type="text/javascript"></script>
</body></html>

Enable legend

Use a legend for the HeatMap in the legendSettings object by setting the visible property to true and injecting the Legend module using the HeatMap.Inject(Legend) method.

index.js
index.html
var heatmapData = [
     [73, 39, 26, 39, 94, 0],
     [93, 58, 53, 38, 26, 68],
     [99, 28, 22, 4, 66, 90],
     [14, 26, 97, 69, 69, 3],
     [7, 46, 47, 47, 88, 6],
     [41, 55, 73, 23, 3, 79],
     [56, 69, 21, 86, 3, 33],
     [45, 7, 53, 81, 95, 79],
     [60, 77, 74, 68, 88, 51],
     [25, 25, 10, 12, 78, 14],
     [25, 56, 55, 58, 12, 82],
     [74, 33, 88, 23, 86, 59]];

var heatmap = new ej.heatmap.HeatMap({
     titleSettings: {
            text: 'Sales Revenue per Employee (in 1000 US$)',
            textStyle: {
                size: '15px',
                fontWeight: '500',
                fontStyle: 'Normal',
                fontFamily: 'Segoe UI'
            }
        },
        xAxis: {
            labels: ['Nancy', 'Andrew', 'Janet', 'Margaret', 'Steven', 
                        'Michael', 'Robert', 'Laura', 'Anne', 'Paul', 'Karin',   'Mario'],
        },
        yAxis: {
            labels: ['Mon', 'Tues', 'Wed', 'Thurs', 'Fri', 'Sat'],
        },
     dataSource: heatmapData, 
      legendSettings: {
            position: 'Right',
            showLabel: true,
            height: "150"
        }  
}, '#element');
<!DOCTYPE html><html lang="en"><head>
    <title>EJ2 HeatMap</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="index.css" rel="stylesheet">
    
    
<script src="https://cdn.syncfusion.com/ej2/28.1.33/dist/ej2.min.js" type="text/javascript"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>

<body>
    
    <div id="container">
        <div id="element"></div>
    </div>


<script>
var ele = document.getElementById('container');
if(ele) {
  ele.style.visibility = "visible";
}   
      </script>
<script src="index.js" type="text/javascript"></script>
</body></html>

Add data label

Add data labels to improve the readability of the HeatMap. This can be achieved by setting the showLabel property to true in the cellSettings object.

index.js
index.html
var heatmapData = [
     [73, 39, 26, 39, 94, 0],
     [93, 58, 53, 38, 26, 68],
     [99, 28, 22, 4, 66, 90],
     [14, 26, 97, 69, 69, 3],
     [7, 46, 47, 47, 88, 6],
     [41, 55, 73, 23, 3, 79],
     [56, 69, 21, 86, 3, 33],
     [45, 7, 53, 81, 95, 79],
     [60, 77, 74, 68, 88, 51],
     [25, 25, 10, 12, 78, 14],
     [25, 56, 55, 58, 12, 82],
     [74, 33, 88, 23, 86, 59]];

var heatmap = new ej.heatmap.HeatMap({
     titleSettings: {
            text: 'Sales Revenue per Employee (in 1000 US$)',
            textStyle: {
                size: '15px',
                fontWeight: '500',
                fontStyle: 'Normal',
                fontFamily: 'Segoe UI'
            }
        },
         cellSettings: {
            showLabel: true,
        },
        xAxis: {
            labels: ['Nancy', 'Andrew', 'Janet', 'Margaret', 'Steven', 
                        'Michael', 'Robert', 'Laura', 'Anne', 'Paul', 'Karin',   'Mario'],
        },
        yAxis: {
            labels: ['Mon', 'Tues', 'Wed', 'Thurs', 'Fri', 'Sat'],
        },
     dataSource: heatmapData, 
      legendSettings: {
            position: 'Right',
            showLabel: true,
            height: "150"
        }  
}, '#element');
<!DOCTYPE html><html lang="en"><head>
    <title>EJ2 HeatMap</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="index.css" rel="stylesheet">
    
    
<script src="https://cdn.syncfusion.com/ej2/28.1.33/dist/ej2.min.js" type="text/javascript"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>

<body>
    
    <div id="container">
        <div id="element"></div>
    </div>


<script>
var ele = document.getElementById('container');
if(ele) {
  ele.style.visibility = "visible";
}   
      </script>
<script src="index.js" type="text/javascript"></script>
</body></html>

Add custom cell palette

The default palette settings of the HeatMap cells can be customized by using the paletteSettings property.
Using the palette property in paletteSettings object, you can change the color set for the cells.
You can change the color mode of the cells to fixed or gradient mode using the type property.

index.js
index.html
var heatmapData = [
     [73, 39, 26, 39, 94, 0],
     [93, 58, 53, 38, 26, 68],
     [99, 28, 22, 4, 66, 90],
     [14, 26, 97, 69, 69, 3],
     [7, 46, 47, 47, 88, 6],
     [41, 55, 73, 23, 3, 79],
     [56, 69, 21, 86, 3, 33],
     [45, 7, 53, 81, 95, 79],
     [60, 77, 74, 68, 88, 51],
     [25, 25, 10, 12, 78, 14],
     [25, 56, 55, 58, 12, 82],
     [74, 33, 88, 23, 86, 59]];

var heatmap = new ej.heatmap.HeatMap({
     titleSettings: {
            text: 'Sales Revenue per Employee (in 1000 US$)',
            textStyle: {
                size: '15px',
                fontWeight: '500',
                fontStyle: 'Normal',
                fontFamily: 'Segoe UI'
            }
        },
         cellSettings: {
            showLabel: true,
        },
        xAxis: {
            labels: ['Nancy', 'Andrew', 'Janet', 'Margaret', 'Steven', 
                        'Michael', 'Robert', 'Laura', 'Anne', 'Paul', 'Karin',   'Mario'],
        },
        yAxis: {
            labels: ['Mon', 'Tues', 'Wed', 'Thurs', 'Fri', 'Sat'],
        },
     dataSource: heatmapData, 
      legendSettings: {
            position: 'Right',
            showLabel: true,
            height: "150"
        },
           paletteSettings: {
            palette: [{ value: 0, color: '#C06C84' },
                { value: 50, color: '#6C5B7B' },
                { value: 100, color: '#355C7D' }                
            ],
            type: "Gradient"
        },  
}, '#element');
<!DOCTYPE html><html lang="en"><head>
    <title>EJ2 HeatMap</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="index.css" rel="stylesheet">
    
    
<script src="https://cdn.syncfusion.com/ej2/28.1.33/dist/ej2.min.js" type="text/javascript"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>

<body>
    
    <div id="container">
        <div id="element"></div>
    </div>


<script>
var ele = document.getElementById('container');
if(ele) {
  ele.style.visibility = "visible";
}   
      </script>
<script src="index.js" type="text/javascript"></script>
</body></html>

The tooltip is used when you cannot display information by using the data labels due to space constraints. You can enable the tooltip by setting the showTooltip property to true and injecting the Tooltip module using the HeatMap.Inject(Tooltip) method.

index.js
index.html
var heatmapData = [
     [73, 39, 26, 39, 94, 0],
     [93, 58, 53, 38, 26, 68],
     [99, 28, 22, 4, 66, 90],
     [14, 26, 97, 69, 69, 3],
     [7, 46, 47, 47, 88, 6],
     [41, 55, 73, 23, 3, 79],
     [56, 69, 21, 86, 3, 33],
     [45, 7, 53, 81, 95, 79],
     [60, 77, 74, 68, 88, 51],
     [25, 25, 10, 12, 78, 14],
     [25, 56, 55, 58, 12, 82],
     [74, 33, 88, 23, 86, 59]];

var heatmap = new ej.heatmap.HeatMap({
     titleSettings: {
            text: 'Sales Revenue per Employee (in 1000 US$)',
            textStyle: {
                size: '15px',
                fontWeight: '500',
                fontStyle: 'Normal',
                fontFamily: 'Segoe UI'
            }
        },
         cellSettings: {
            showLabel: true,
        },
        xAxis: {
            labels: ['Nancy', 'Andrew', 'Janet', 'Margaret', 'Steven', 
                        'Michael', 'Robert', 'Laura', 'Anne', 'Paul', 'Karin',   'Mario'],
        },
        yAxis: {
            labels: ['Mon', 'Tues', 'Wed', 'Thurs', 'Fri', 'Sat'],
        },
     dataSource: heatmapData, 
      legendSettings: {
            position: 'Right',
            showLabel: true,
            height: "150"
        },
        showTooltip:true,  
        
}, '#element');
<!DOCTYPE html><html lang="en"><head>
    <title>EJ2 HeatMap</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="index.css" rel="stylesheet">
    
    
<script src="https://cdn.syncfusion.com/ej2/28.1.33/dist/ej2.min.js" type="text/javascript"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>

<body>
    
    <div id="container">
        <div id="element"></div>
    </div>


<script>
var ele = document.getElementById('container');
if(ele) {
  ele.style.visibility = "visible";
}   
      </script>
<script src="index.js" type="text/javascript"></script>
</body></html>

Getting started in EJ2 JavaScript Heatmap chart control

control Initialization

Using local script and style references in a HTML page

Using CDN link for script and style reference

Populate HeatMap with data

Enable axis labels

Add HeatMap title

Enable legend

Add data label

Add custom cell palette

Enable tooltip