Spline Area Chart in EJ2 JavaScript Charts

7 May 202524 minutes to read

Spline Area

To render a spline area series in your chart, you need to follow a few steps to configure it correctly. Here’s a concise guide on how to do this:

  • Set the series type: Define the series type as SplineArea in your chart configuration. This indicates that the data should be represented as a spline area chart, where data points are connected by smooth, curved lines (splines) instead of straight lines.
var chartData = [
    { x: 'Jan', y: -1 }, { x: 'Feb', y: -1 }, { x: 'Mar', y: 2 },
    { x: 'Apr', y: 8 },  { x: 'May', y: 13 }, { x: 'Jun', y: 18 },
    { x: 'Jul', y: 21 }, { x: 'Aug', y: 20 }, { x: 'Sep', y: 16 },
    { x: 'Oct', y: 10 }, { x: 'Nov', y: 4 },  { x: 'Dec', y: 0 }
];
var chart = new ej.charts.Chart({
    primaryXAxis: {
        valueType: 'Category',
        title: 'Month'
    },
    primaryYAxis: {
        minimum: -5, maximum: 30, interval: 5,
        title: 'Temperature in Celsius',
        labelFormat: '{value}°C'
    },
    series:[{
        dataSource: chartData,
        xName: 'x', yName: 'y',
        // Series type as spline area series
        type: 'SplineArea'
    }],
    title: 'Climate Graph-2012'
}, '#element');
<!DOCTYPE html>
<html lang="en">

<head>
    <title>EJ2 Animation</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/ej2/29.2.4/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>

Binding data with series

You can bind data to the chart using the dataSource property within the series configuration. This allows you to connect a JSON dataset or remote data to your chart. To display the data correctly, map the fields from the data to the chart series xName and yName properties.

var chartData = [
    { x: 'Jan', y: -1 }, { x: 'Feb', y: -1 }, { x: 'Mar', y: 2 },
    { x: 'Apr', y: 8 },  { x: 'May', y: 13 }, { x: 'Jun', y: 18 },
    { x: 'Jul', y: 21 }, { x: 'Aug', y: 20 }, { x: 'Sep', y: 16 },
    { x: 'Oct', y: 10 }, { x: 'Nov', y: 4 },  { x: 'Dec', y: 0 }
];
var chart = new ej.charts.Chart({
    primaryXAxis: {
        valueType: 'Category',
        title: 'Month'
    },
    primaryYAxis: {
        minimum: -5, maximum: 30, interval: 5,
        title: 'Temperature in Celsius',
        labelFormat: '{value}°C'
    },
    series:[{
        dataSource: chartData,
        xName: 'x', yName: 'y',
        // Series type as spline area series
        type: 'SplineArea'
    }],
    title: 'Climate Graph-2012'
}, '#element');
<!DOCTYPE html>
<html lang="en">

<head>
    <title>EJ2 Animation</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/ej2/29.2.4/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>

Series customization

The following properties can be used to customize the spline area series.

Fill

The fill property determines the color applied to the series.

var chartData = [
    { x: 'Jan', y: -1 }, { x: 'Feb', y: -1 }, { x: 'Mar', y: 2 },
    { x: 'Apr', y: 8 },  { x: 'May', y: 13 }, { x: 'Jun', y: 18 },
    { x: 'Jul', y: 21 }, { x: 'Aug', y: 20 }, { x: 'Sep', y: 16 },
    { x: 'Oct', y: 10 }, { x: 'Nov', y: 4 },  { x: 'Dec', y: 0 }
];
var chart = new ej.charts.Chart({
    primaryXAxis: {
        valueType: 'Category',
        title: 'Month'
    },
    primaryYAxis: {
        minimum: -5, maximum: 30, interval: 5,
        title: 'Temperature in Celsius',
        labelFormat: '{value}°C'
    },
    series:[{
        dataSource: chartData,
        xName: 'x', yName: 'y',
        // Series type as spline area series
        type: 'SplineArea',
        fill: 'blue'
    }],
    title: 'Climate Graph-2012'
}, '#element');
<!DOCTYPE html>
<html lang="en">

<head>
    <title>EJ2 Animation</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/ej2/29.2.4/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 fill property can be used to apply a gradient color to the spline area series. By configuring this property with gradient values, you can create a visually appealing effect in which the color transitions smoothly from one shade to another.

var chartData = [
    { x: 'Jan', y: -1 }, { x: 'Feb', y: -1 }, { x: 'Mar', y: 2 },
    { x: 'Apr', y: 8 },  { x: 'May', y: 13 }, { x: 'Jun', y: 18 },
    { x: 'Jul', y: 21 }, { x: 'Aug', y: 20 }, { x: 'Sep', y: 16 },
    { x: 'Oct', y: 10 }, { x: 'Nov', y: 4 },  { x: 'Dec', y: 0 }
];
var chart = new ej.charts.Chart({
    primaryXAxis: {
        valueType: 'Category',
        title: 'Month'
    },
    primaryYAxis: {
        minimum: -5, maximum: 30, interval: 5,
        title: 'Temperature in Celsius',
        labelFormat: '{value}°C'
    },
    series:[{
        dataSource: chartData,
        xName: 'x', yName: 'y',
        // Series type as spline area series
        type: 'SplineArea',
        fill: 'url(#gradient)'
    }],
    title: 'Climate Graph-2012'
}, '#element');
<!DOCTYPE html>
<html lang="en">

<head>
    <title>EJ2 Animation</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/ej2/29.2.4/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>
    <svg style="width:1px; height:1px">
        <defs>
            <linearGradient id="gradient">
                <stop offset="0%" style="stop-color: blue; stop-opacity:5" />
                <stop offset="50%" style="stop-color: violet; stop-opacity:5" />
            </linearGradient>
        </defs>
    </svg>
    <script>
        var ele = document.getElementById('container');
        if (ele) {
            ele.style.visibility = "visible";
        }   
    </script>
    <script src="index.js" type="text/javascript"></script>
</body>

</html>

Opacity

The opacity property specifies the transparency level of the fill. Adjusting this property allows you to control how opaque or transparent the fill color of the series appears.

var chartData = [
    { x: 'Jan', y: -1 }, { x: 'Feb', y: -1 }, { x: 'Mar', y: 2 },
    { x: 'Apr', y: 8 },  { x: 'May', y: 13 }, { x: 'Jun', y: 18 },
    { x: 'Jul', y: 21 }, { x: 'Aug', y: 20 }, { x: 'Sep', y: 16 },
    { x: 'Oct', y: 10 }, { x: 'Nov', y: 4 },  { x: 'Dec', y: 0 }
];
var chart = new ej.charts.Chart({
    primaryXAxis: {
        valueType: 'Category',
        title: 'Month'
    },
    primaryYAxis: {
        minimum: -5, maximum: 30, interval: 5,
        title: 'Temperature in Celsius',
        labelFormat: '{value}°C'
    },
    series:[{
        dataSource: chartData,
        xName: 'x', yName: 'y',
        // Series type as spline area series
        type: 'SplineArea',
        opacity: 0.5
    }],
    title: 'Climate Graph-2012'
}, '#element');
<!DOCTYPE html>
<html lang="en">

<head>
    <title>EJ2 Animation</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/ej2/29.2.4/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>

Border

Use the border property to customize the width, color and dasharray of the series border.

var chartData = [
    { x: 'Jan', y: -1 }, { x: 'Feb', y: -1 }, { x: 'Mar', y: 2 },
    { x: 'Apr', y: 8 },  { x: 'May', y: 13 }, { x: 'Jun', y: 18 },
    { x: 'Jul', y: 21 }, { x: 'Aug', y: 20 }, { x: 'Sep', y: 16 },
    { x: 'Oct', y: 10 }, { x: 'Nov', y: 4 },  { x: 'Dec', y: 0 }
];
var chart = new ej.charts.Chart({
    primaryXAxis: {
        valueType: 'Category',
        title: 'Month'
    },
    primaryYAxis: {
        minimum: -5, maximum: 30, interval: 5,
        title: 'Temperature in Celsius',
        labelFormat: '{value}°C'
    },
    series:[{
        dataSource: chartData,
        xName: 'x', yName: 'y',
        // Series type as spline area series
        type: 'SplineArea',
        border: { width: 2, color: '#FFA500', dashArray: '5,5' }
    }],
    title: 'Climate Graph-2012'
}, '#element');
<!DOCTYPE html>
<html lang="en">

<head>
    <title>EJ2 Animation</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/ej2/29.2.4/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>

Empty points

Data points with null or undefined values are considered empty. Empty data points are ignored and not plotted on the chart.

Mode

Use the mode property to define how empty or missing data points are handled in the series. The default mode for empty points is Gap.

var chartData = [
    { x: 'Jan', y: -1 }, { x: 'Feb', y: -1 }, { x: 'Mar', y: 2 },
    { x: 'Apr', y: null },  { x: 'May', y: 13 }, { x: 'Jun', y: 18 },
    { x: 'Jul', y: 21 }, { x: 'Aug', y: 20 }, { x: 'Sep', y: undefined },
    { x: 'Oct', y: 10 }, { x: 'Nov', y: 4 },  { x: 'Dec', y: 0 }
];
var chart = new ej.charts.Chart({
    primaryXAxis: {
        valueType: 'Category',
        title: 'Month'
    },
    primaryYAxis: {
        minimum: -5, maximum: 30, interval: 5,
        title: 'Temperature in Celsius',
        labelFormat: '{value}°C'
    },
    series:[{
        dataSource: chartData,
        xName: 'x', yName: 'y',
        // Series type as spline area series
        type: 'SplineArea',
        emptyPointSettings: {
            mode: 'Average'
        }
    }],
    title: 'Climate Graph-2012'
}, '#element');
<!DOCTYPE html>
<html lang="en">

<head>
    <title>EJ2 Animation</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/ej2/29.2.4/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>

Fill

Use the fill property to customize the fill color of empty points in the series.

var chartData = [
    { x: 'Jan', y: -1 }, { x: 'Feb', y: -1 }, { x: 'Mar', y: 2 },
    { x: 'Apr', y: null },  { x: 'May', y: 13 }, { x: 'Jun', y: 18 },
    { x: 'Jul', y: 21 }, { x: 'Aug', y: 20 }, { x: 'Sep', y: undefined },
    { x: 'Oct', y: 10 }, { x: 'Nov', y: 4 },  { x: 'Dec', y: 0 }
];
var chart = new ej.charts.Chart({
    primaryXAxis: {
        valueType: 'Category',
        title: 'Month'
    },
    primaryYAxis: {
        minimum: -5, maximum: 30, interval: 5,
        title: 'Temperature in Celsius',
        labelFormat: '{value}°C'
    },
    series:[{
        dataSource: chartData,
        xName: 'x', yName: 'y',
        // Series type as spline area series
        type: 'SplineArea',
        marker: { visible: true, width: 7, height: 7, isFilled: true },
        emptyPointSettings: {
            mode: 'Average',
            fill: 'red'
        }
    }],
    title: 'Climate Graph-2012'
}, '#element');
<!DOCTYPE html>
<html lang="en">

<head>
    <title>EJ2 Animation</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/ej2/29.2.4/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>

Border

Use the border property to customize the width and color of the border for empty points.

var chartData = [
    { x: 'Jan', y: -1 }, { x: 'Feb', y: -1 }, { x: 'Mar', y: 2 },
    { x: 'Apr', y: null },  { x: 'May', y: 13 }, { x: 'Jun', y: 18 },
    { x: 'Jul', y: 21 }, { x: 'Aug', y: 20 }, { x: 'Sep', y: undefined },
    { x: 'Oct', y: 10 }, { x: 'Nov', y: 4 },  { x: 'Dec', y: 0 }
];
var chart = new ej.charts.Chart({
    primaryXAxis: {
        valueType: 'Category',
        title: 'Month'
    },
    primaryYAxis: {
        minimum: -5, maximum: 30, interval: 5,
        title: 'Temperature in Celsius',
        labelFormat: '{value}°C'
    },
    series:[{
        dataSource: chartData,
        xName: 'x', yName: 'y',
        // Series type as spline area series
        type: 'SplineArea',
        marker: { visible: true, width: 7, height: 7, isFilled: true },
        emptyPointSettings: {
            mode: 'Average',
            fill: 'red',
            border: { width: 2, color: 'green' }
        }
    }],
    title: 'Climate Graph-2012'
}, '#element');
<!DOCTYPE html>
<html lang="en">

<head>
    <title>EJ2 Animation</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/ej2/29.2.4/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>

Events

Series render

The seriesRender event allows you to customize series properties, such as data, fill, and name, before they are rendered on the chart.

var chartData = [
    { x: 'Jan', y: -1 }, { x: 'Feb', y: -1 }, { x: 'Mar', y: 2 },
    { x: 'Apr', y: 8 },  { x: 'May', y: 13 }, { x: 'Jun', y: 18 },
    { x: 'Jul', y: 21 }, { x: 'Aug', y: 20 }, { x: 'Sep', y: 16 },
    { x: 'Oct', y: 10 }, { x: 'Nov', y: 4 },  { x: 'Dec', y: 0 }
];
var chart = new ej.charts.Chart({
    primaryXAxis: {
        valueType: 'Category',
        title: 'Month'
    },
    primaryYAxis: {
        minimum: -5, maximum: 30, interval: 5,
        title: 'Temperature in Celsius',
        labelFormat: '{value}°C'
    },
    series:[{
        dataSource: chartData,
        xName: 'x', yName: 'y',
        // Series type as spline area series
        type: 'SplineArea'
    }],
    title: 'Climate Graph-2012',
    seriesRender: function (args) {
        args.fill = '#ff6347';
    }
}, '#element');
<!DOCTYPE html>
<html lang="en">

<head>
    <title>EJ2 Animation</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/ej2/29.2.4/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>

Point render

The pointRender event allows you to customize each data point before it is rendered on the chart.

var chartData = [
    { x: 'Jan', y: -1 }, { x: 'Feb', y: -1 }, { x: 'Mar', y: 2 },
    { x: 'Apr', y: 8 },  { x: 'May', y: 13 }, { x: 'Jun', y: 18 },
    { x: 'Jul', y: 21 }, { x: 'Aug', y: 20 }, { x: 'Sep', y: 16 },
    { x: 'Oct', y: 10 }, { x: 'Nov', y: 4 },  { x: 'Dec', y: 0 }
];
var chart = new ej.charts.Chart({
    primaryXAxis: {
        valueType: 'Category',
        title: 'Month'
    },
    primaryYAxis: {
        minimum: -5, maximum: 30, interval: 5,
        title: 'Temperature in Celsius',
        labelFormat: '{value}°C'
    },
    series:[{
        dataSource: chartData,
        xName: 'x', yName: 'y',
        // Series type as spline area series
        type: 'SplineArea',
        marker: { visible: true, isFilled: true, width: 7, height: 7 }
    }],
    title: 'Climate Graph-2012',
    pointRender: function (args) {
        if (args.point.y < 10) {
            args.fill = '#ff6347';
        }
        else {
            args.fill = '#009cb8';
        }
    }
}, '#element');
<!DOCTYPE html>
<html lang="en">

<head>
    <title>EJ2 Animation</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/ej2/29.2.4/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>

See also