how to use canvas's js code example
Example 1: javascript canvas
<canvas id="canvas"></canvas>
<script>
var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');
ctx.beginPath();
ctx.rect(x, y, width, height);
ctx.fillStyle = 'limegreen';
ctx.fill();
ctx.beginPath();
ctx.arc(x, y, radius, startAngle, endAngle, counterClockWise(optional));
ctx.strokeStyle = 'black';
ctx.stroke();
</script>
Example 2: canvas in javascript
<!DOCTYPE HTML>
<html>
<head>
<style>
#mycanvas{border:1px solid red;}
</style>
</head>
<body>
<canvas id = "mycanvas" width = "100" height = "100"></canvas>
</body>
</html>