<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>标题</title>
</head>
<body>
<!-- canvas是一个画布，需要使用脚本来绘制图形 -->
<!-- height和width规定画布的大小 -->
<canvas id="canvas_id" height="500" width="500"></canvas>
<script type="text/javascript">
var canvas = document.getElementById('canvas_id');
var ctx = canvas.getContext('2d');
ctx.fillStyle = '#24acf2';
ctx.fillRect(0, 0, 100, 100);
ctx.fillRect(100, 100, 500, 500);
</script>
</body>
</html>
