看了很久，还是不知道哪里错了。。。。

var WINDOW.WIDTH=1024;

var WINDOW.HEIGHT=768;

var RADIUS=8;

window.onload=function(){

var canvas=getElementById('canvas');

    var context=canvas.context("2d");

    canvas.width=WINDOW.WIDTH;

    canvas.height=WINDOW.HEIGHT;

    render(context);

}

function render(cxt){

var hours=12

var minutes=34

var seconds=56

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();

}

}