<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
</head>
<body>
<div>
<canvas id="canvas" width="" height=""></canvas>
</div>
<script type="text/javascript">
var canvas = document.getElementById("canvas"); //获取到canvas元素
canvas.width = 800;
canvas.height = 800;
var context = canvas.getContext("2d"); //获取上下文的环境
context.lineWidth = 50;
context.strokeStyle = "#005588";
context.beginPath();
context.moveTo(100, 200);
context.lineTo(700, 200);
context.lineCap = "butt";
context.stroke();
context.beginPath();
context.moveTo(100, 400);
context.lineTo(700, 400);
context.lineCap = "round";
context.stroke();
context.beginPath();
context.moveTo(100, 600);
context.lineTo(700, 600);
context.lineCap = "square";
context.stroke();
</script>
</body>
</html>