javascript - 用drawImage把画布画到画布上，为什么有的浏览器不显示？
<canvas id="canvas" width=800 height=500></canvas>
<script type="text/javascript">
function GED(ele){
return document.getElementById(ele);
}
canvas = GED('canvas');
ctx = canvas.getContext('2d');
var img = new Image();
img.src='nor1.png';
var canvasOffscreen = document.createElement('canvas');
canvasOffscreen.width = 500;
canvasOffscreen.height = 500;
function draw(){
ctx.clearRect(0,0,500,500);
if (img.complete){
ctx.drawImage(canvasOffscreen,0,0);
}else{
img.onload = function(){
canvasOffscreen.getContext('2d').drawImage(this,0,0,500,500,0,0,500,500);
ctx.drawImage(canvasOffscreen,0,0);
}
}
}
draw();
</script>
服务器用了，额，是火狐浏览器
--最新详细
火狐浏览器49 第一次打开第一次加载可以显示，没问题，然后刷新就再也不显示了！
