demo.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>canvas</title>
<link rel="stylesheet" type="text/css" href="demo.css">
<script type="text/javascript" src="demo.js"></script>
</head>
<body>
<canvas id="mycanvas" width="600px" height="800px" >
<span>你的浏览器不支持canvas</span>
</canvas>
</body>
</html>
demo.js
window.onload=function() {
createcanvas();
drawcanvas();
}
function createcanvas() {
var CANVAS=document.getElementById('mycanvas');
context=CANVAS.getContext('2d');
}
function drawcanvas() {
context.fillStyle="#eeeeef";
context.fillRect(0,0,600,800);
for(var i=0;i<=10;i++) {
context.beginPath();
context.arc(i*25,i*25,i*10,0,Math.PI*2,true);
context.closePath();
context.fillStyle="rgba(255,0,0,0.25)";
context.fill();
}
}
效果：
2017-09-08 08:36:44