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Fabric.js | Circle opacity Property

  • Last Updated : 12 Jul, 2021

In this article, we are going to see how to set the opacity of a canvas circle using FabricJS. The canvas means the circle is movable and can be stretched according to requirement. Further, the circle can be customized when it comes to initial stroke color, fill color, stroke width, or radius.
Approach: To make it possible we are going to use a JavaScript library called FabricJS. After importing the library using CDN, we will create a canvas block in the body tag which will contain our circle. After this, we will initialize instances of Canvas and Circle provided by FabricJS and set the opacity of the circle using opacity property and render the Circle on the Canvas as given in the example below.

    radius: number,
    opacity: number

Parameters: This function accepts two parameters as mentioned above and described below: 

  • radius: It specifies the radius of circle.
  • opacity: It specifies the opacity of the circle canvas.

Example: This example uses FabricJS to set opacity of a canvas circle.


<!DOCTYPE html>
        Fabric.js | Circle opacity Property
    <!-- FabricJS CDN -->
    <script src=
    <canvas id="canvas" width="600" height="200"
        style="border:1px solid #000000">
        // Initiate a Canvas instance
        var canvas = new fabric.Canvas("canvas");
        // Initiate a Circle instance
        var circle = new fabric.Circle({
            radius: 50,
            opacity: 1
        // Render the circle in canvas



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