                        課程
                    
                        /前端開發
                        
                            /Html5
                        
                        /炫麗的倒計時效果Canvas繪圖與動畫基礎

怎么什么都顯示不出來??？看了好幾遍，都沒找出錯誤在哪？

<!DOCTYPE html>
<html>
<head>
??? <meta charset="UTF-8">
??? <title></title>
</head>
<body>
<canvas id="canvas" style="border:1px solid blue;display: block">
</canvas>
<script type="text/javascript">
??? var WINDOW_WIDTH=1024;
??? var WINDOW_HEIGHT=768;
??? var RADIUS=8;
window.onload=function(){
??? var canvas = document.getElementById("canvas");
??? canvas.width = WINDOW_WIDTH;
??? canvas.height = WINDOW_HEIGHT;
??? var context = canvas.getContext("2d");
??? render(context)
}

function render(cxt){
??? //定義時鐘變量
??????? var hours=12;
??????? var miniutes=24;
??????? var seconds=48;
??? renderDigit(0,0,parseInt(hours/10),cxt)
}
function renderDigit(x,y,num,cxt){
??? cxt.fillStyle="rgb(0,102,153)";
??? for(var i=0;i<digit[num].length;i++)
?????? for(var j=0;j<digit[num][i].length;j++)
???????? if(digit[num][i][j]==1){
???????????? cxt.beginPath();
???????????? cxt.arc(x+j*2*(RADIUS+1)+(RADIUS+1),y+i*2*(RADIUS+1)+(RADIUS+1),RADIUS,0,2*Math.PI);
???????????? cxt.closePath();
???????????? cxt.fill();
???????????? cxt.stroke();
???????? }

??? }
</script>
</body>
</html>