为什么在浏览器上显示不出来图形
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title></title>
</head>
<body>
<canvas id="canvas" style="border:1px solid #aaa;display:block;margin:50px auto;">
</canvas>
<script>
var tangram = [
{p:[{x:0,y:0},{x:800,y:0},{x:400,y:400}],color:"blue"},
{p:[{x:0,y:0},{x:400,y:400},{x:0,y:800}],color:"black"},
{p:[{x:800,y:0},{x:800,y:400},{x:600,y:600},{x:600,y:200}],color:"red"},
{p:[{x:600,y:200},{x:600,y:600},{x:400,y:400}],color:"yellow"},
{p:[{x:400,y:400},{x:600,y:600},{x:400,y:800},{x:200,y:600}],color:"orange"},
{p:[{x:200,y:600},{x:400,y:800},{x:0,y:800}],color:"pink"},
{p:[{x:800,y:400},{x:800,y:800},{x:400,y:800}],color:"#purple"},
]
window.onload = function(){
var canvas = document.getElementById("canvas");
canvas.width = 800;
canvas.height = 800;
var context = canvas.getContext("2d");
for( var i = 0; i < tangram.length ; i ++)
draw( tangram[i],context)
}
function draw(piece, cxt){
cxt.beginPath();
cxt.moveTo(piece.p[0].x,piece.p[0].y);
for(var i = 1;i < piece.p.length; i ++)
cxt.lineTo(piece.p[i].x,piece.p[i].y);
cxt.closePath();
cxt.fillStyle = piece.color;
ext.fill();
cxt.strockStyle = "black"
cxt.lineWidth = 3;
cxt.strock();
}
</script>
</body>
</html>
显示不出来图案
