How to clear the canvas using clearRect in HTML ?

Last Updated : 27 Jan, 2022

The clearRect() method of the Canvas 2D API which is used to erase the pixel in a rectangular area by setting the pixel color to transparent black (rgba(0, 0, 0, 0)).
Syntax:

abc.clearRect(x, y, width, height);

Parameters:

x, y: These parameter represents the top-left coordinate of the rectangular box.
width: It is used to set the width of the rectangular box
height: It is used to set the of the rectangular box

Example 1: In the following example the clearRect() method is used to clear the pixel of a rectangle of size (200x300) from (50, 20).

html

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

<head>
    <title>
        How to clear the canvas
        using clearRect in HTML?
    </title>
</head>

<body>
    <canvas id="canvas"></canvas>

    <script>
        const canvas = document.getElementById("canvas");
        const abc = canvas.getContext('2d');
    
        abc.beginPath();
        abc.fillStyle = "red";
        abc.fillRect(0, 0, 200, 300);
    
        abc.clearRect(50, 20, 100, 100);
    </script>
</body>

</html>

Output:

Example 2:

html

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

<head>
    <title>
        How to clear the canvas
        using clearRect in HTML?
    </title>
</head>

<body>
    <canvas id="canvas"></canvas>

    <script>
        const canvas = document.getElementById("canvas");
        const abc = canvas.getContext('2d');
         
        // Draws a rectangle of 200x300
        abc.beginPath();
        abc.fillStyle = "red";
        abc.fillRect(0, 0, 200, 300);
         
        // Draws a triangle
        abc.beginPath();
        abc.fillStyle = "green";
        abc.moveTo(10, 10);
        abc.lineTo(150, 10);
        abc.lineTo(120, 120);
        abc.closePath();
        abc.fill();
     
        abc.clearRect(40, 25, 100, 70);
    </script>
</body>

</html>

Output:

Example 3: In this example we will erase whole canvas.

html

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

<head>
    <title>
        How to clear the canvas
        using clearRect in HTML?
    </title>
</head>

<body>
    <canvas id="canvas"></canvas>

    <script>
        const canvas = document.getElementById("canvas");
        const abc = canvas.getContext('2d');
     
        abc.beginPath();
        abc.fillStyle = "red";
        abc.fillRect(0, 0, 200, 300);
         
        // This line will erase whole canvas and
        // we will get an empty screen
        abc.clearRect(0, 0, canvas.width, canvas.height);
    </script>
</body>

</html>

Note: Be aware that clearRect() may cause unintended side effects if you're not using paths properly. Make sure to call beginPath() before starting to draw new items after calling clearRect().
Reference: https://www.geeksforgeeks.org/html-canvas-clearrect-method/

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