var WINDOW_WIDTH=1024;

var WINDOW_HEIGHT=768;

var RADIUS=8;

var MARGIN_TOP=60;

var MARGIN_LEFT=30;

const endTime = new Date(2014,6,11,18,47,52);

var curShowTimeSeconds=0;

var balls=[];

const colors = ["#33B5E5","#0099CC","#AA66CC","#9933CC","#99CC00","#669900","#FFBB33","#FF8800","#FF4444","#CC0000"]

window.onload=function(){

    //   /** @type {HTMLCanvasElement} */ /

    var canvas=document.getElementById('canvas');

    var context=canvas.getContext('2d');

    canvas.width=WINDOW_WIDTH;

    canvas.height=WINDOW_HEIGHT;

    curShowTimeSeconds=getCurrentShowTimeSeconds()

    // render(context)

    setInterval(

        function(){

            render(context)

            update()

        },50

    );

}

function getCurrentShowTimeSeconds(){

    //  /** @type {HTMLCanvasElement} */ 

    var curTime=new Date();

    var ret=endTime.getTime()-curTime.getTime();

        ret= Math.round(ret/1000)

    return ret >= 0 ? ret : 0;

}

function update(){

    //  /** @type {HTMLCanvasElement} */ 

    var nextShowTimeSeconds=getCurrentShowTimeSeconds();

    var nextHours=parseInt( nextShowTimeSeconds/3600 );

    var nextMinutes=parseInt( (nextShowTimeSeconds-nextHours*3600)/60 );

    var nextSeconds=nextShowTimeSeconds%60;

    var curHours=parseInt( curShowTimeSeconds/3600 );

    var curMinutes=parseInt( (curShowTimeSeconds-curHours*3600)/60 );

    var curSeconds=curShowTimeSeconds%60;

    if(nextSeconds !=curSeconds){

        curShowTimeSeconds=nextShowTimeSeconds;

    }

}

function render(cxt) {

    //  /** @type {HTMLCanvasElement} */ //获得canvas语法提示

    cxt.clearRect(0,0,WINDOW_WIDTH,WINDOW_HEIGHT);

    var hours=parseInt( curShowTimeSeconds/3600 );

    var minutes=parseInt( (curShowTimeSeconds-hours*3600)/60 );

    var seconds=curShowTimeSeconds%60;

    renderDigit(MARGIN_LEFT,MARGIN_TOP,parseInt(hours/10),cxt)

    renderDigit(MARGIN_LEFT+15*(RADIUS+1),MARGIN_TOP,parseInt(hours%10),cxt)

    renderDigit(MARGIN_LEFT+30*(RADIUS+1),MARGIN_TOP,10,cxt)

    renderDigit(MARGIN_LEFT+39*(RADIUS+1),MARGIN_TOP,parseInt(minutes/10),cxt)

    renderDigit(MARGIN_LEFT+54*(RADIUS+1),MARGIN_TOP,parseInt(minutes%10),cxt)

    renderDigit(MARGIN_LEFT+69*(RADIUS+1),MARGIN_TOP,10,cxt)

    renderDigit(MARGIN_LEFT+78*(RADIUS+1),MARGIN_TOP,parseInt(seconds/10),cxt)

    renderDigit(MARGIN_LEFT+93*(RADIUS+1),MARGIN_TOP,parseInt(seconds%10),cxt)

}

function renderDigit(x,y,num,cxt){

        // /** @type {HTMLCanvasElement} */ //获得canvas语法提示

    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()

         }

}

贴个代码啊亲，以后问问题建议贴代码，要不大家也没法定位问题的