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JavaScript - how to clear canvas with specific color?

6 points
Created by:
Root-ssh
133870

In this article, we would like to show how to clear canvas element using specific color in JavaScript.

To clear canvas with specific color it is necessary to use fillRect() function.

Quick solution:

context.fillStyle = 'yellow';  // color format: 'yellow', '#FFFF00', 'rgb(255,255,0)' or 'rgba(255,255,0,1)'
context.fillRect(0, 0, canvas.width, canvas.height);

 

Reusable function

function clearCanvas(canvas, context, color) {
    context.fillStyle = color;
    context.fillRect(0, 0, canvas.width, canvas.height);
}

Practical example

// ONLINE-RUNNER:browser;

<!doctype html>
<html>
<head>
  <style>
    
    #my-canvas { border: 1px solid gray; }
    
  </style>
</head>
<body>
  <button onclick="drawCircle()">Draw circle!</button>
  <button onclick="clearCanvas('yellow')">Clear canvas!</button>
  <br /><br />
  <canvas id="my-canvas" width="200" height="200"></canvas>
  <script>

    var canvas = document.querySelector('#my-canvas');
    var context = canvas.getContext('2d');

    var xCenter = canvas.width / 2;
    var yCenter = canvas.height / 2;
    var circleRadius = 80;
    
    function drawCircle() {
        context.lineWidth = 5.0;
        context.strokeStyle = '#0000ff';
        context.fillStyle = '#ff0000';
        context.beginPath();
        context.arc(xCenter, yCenter , circleRadius, 0, 2 * Math.PI);
        context.fill();
    }

    function clearCanvas(color) {
        context.fillStyle = color;
        context.fillRect(0, 0, canvas.width, canvas.height);
    }

    clearCanvas('yellow');  // color format: 'yellow', '#FFFF00', 'rgb(255,255,0)' or 'rgba(255,255,0,1)'
    drawCircle();

  </script>
</body>
</html>

 

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JavaScript - HTML5 canvas tutorial

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