​x
 
<!DOCTYPE html>
<html>
<body>
​
<h1>演示如何访问 CANVAS 元素</h1>
​
<canvas id="myCanvas" width="300" height="150" style="border:1px solid #d3d3d3;">
您的浏览器不支持 HTML5 canvas 标签。
</canvas>
​
<p>单击按钮可在画布上绘图。</p>
​
<button onclick="myFunction()">试一试</button>
​
<script>
function myFunction() {
  var c = document.getElementById("myCanvas");
  var ctx = c.getContext("2d");
  ctx.fillStyle = "#FF0000";
  ctx.fillRect(20, 20, 150, 100);
}
</script>
​
</body>
</html>
​