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Fabric.js | Rect borderOpacityWhenMoving Property

  • Last Updated : 11 Jun, 2021

In this article, we are going to see how to set the moving border opacity of a canvas rectangle using FabricJS. The canvas means rectangle is movable and can be stretched according to requirement. Further, the rectangle can be customized when it comes to initial stroke color, fill color, stroke width, or size.
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 rectangle. After this, we will initialize instances of Canvas and Rect provided by FabricJS and set the moving border opacity of the canvas rectangle using borderOpacityWhenMoving property and render the Rect on the Canvas as given in the example below.

    width: number,
    height: number,
    borderOpacityWhenMoving: number

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

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  • width: It specifies the horizontal length.
  • height: It specifies the vertical length.
  • borderOpacityWhenMoving: It specifies the moving border opacity.

Example: This example uses FabricJS to set moving border opacity of the canvas rectangle. Note that you have to move the object to see the moving border opacity. 


<!DOCTYPE html>
        Fabric.js | Rect borderOpacityWhenMoving Property
    <!-- FabricJS CDN -->
    <script src=
    <div style="text-align: center;width: 600px;">
        <h1 style="color: green;">
            Fabric.js | Rect borderOpacityWhenMoving Property
    <div style="text-align: center;">
    <canvas id="canvas" width="600" height="200"
            style="border:1px solid #000000;">
        // Initiate a Canvas instance
        var canvas = new fabric.Canvas("canvas");
        // Initiate a Rect instance
        var rect = new fabric.Rect({
            width: 200,
            height: 100,
            borderOpacityWhenMoving: 0
        // Render the rectangle in canvas



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