效果：
html:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>digit</title>
</head>
<body>
<canvas id="canvas"></canvas>
<script src="digit_1.js"></script>
<script src="countdown.js"></script>
</body>
</html>
countdown.js:
var WINDOW_WIDTH = 1024; var WINDOW_HEIGHT = 768; var RADIUS = 8; var MARGIN_TOP = 60; var MARGIN_LEFT = 30; const endTime = new Date(2017,8,17,18,30,00);//const声明变量，不可修改，必须声明时赋值； var curShowTimeSeconds = 0; window.onload = function () { var canvas = document.getElementById("canvas"); var context = canvas.getContext("2d"); canvas.width = WINDOW_WIDTH; canvas.height = WINDOW_HEIGHT; curShowTimeSeconds = getCurrentShowTimeSeconds(); setInterval( function () { update(); render(context); },50) }; function getCurrentShowTimeSeconds() { var curTime = new Date();//获取目前时间； var ret = endTime.getTime()-curTime.getTime(); ret = Math.round(ret/1000);//获取秒数差值； return ret>=0?ret:0; } function update() { 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) { //每一帧都要对动画进行刷新，不然就会新的旧的叠在一起； cxt.clearRect(0,0,WINDOW_WIDTH,WINDOW_HEIGHT);//对一个矩形空间里的动画进行刷新； 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++){//数组行 for(var j=0;j<digit[num][i].length;j++){//数组列 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(); } } } }