幫我看看countdown.js代碼，對比沒有問題啊，顯示一直是00:00:00呢，當前日期是：2016/1/19。

var WINDOW_WIDTH =1024;
var WINDOW_HEIGHT = 768;
var RADIUS =8;
var MARGIN_TOP=60;
var MARGIN_LEFT=30;
const endTime =new Date(2016,0,17,15,47,52);
var curShowTimeSeconds = 0;
window.onload = function(){
?? ?var canvas = document.getElementById("canvas");
?? ?var cxt =canvas.getContext("2d");

?? ?canvas.width =WINDOW_WIDTH;
?? ?canvas.height = WINDOW_HEIGHT;
?? ?curShowTimeSeconds =getCurrentShowTimeSeconds()
?? ?render(cxt)
?}
function getCurrentShowTimeSeconds(){

?? ?var curTime = new Date();
??? var ret = endTime.getTime() - curTime.getTime();
??? ret = Math.round( ret/1000 )

??? return ret >= 0 ? ret : 0;}

function render(cxt){
??? ? 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){
??? ?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()
??? ??? ??? ?}


?}