<!doctype html> <html lang="en"> <head> <meta charset="UTF-8"> <title>JS</title> <style> #box{ width:600px; height:60px; line-height:60px; font-size:40px; text-align:center; border:3px solid pink; background-color:#f5f5f5; color:pink; } </style> </head> <body> <h1>倒计时</h1> <hr> <div id="box"> </div> <script> //设计倒计时的时限 var seconds = 400000; runTime(); //声明函数 function runTime(){ //计算小时 var h = Math.floor(seconds / 3600); var s = seconds - h * 3600; //计算分钟 var m = Math.floor(s / 60); //计算秒 s -= m * 60; //处理 var h = (h<10)?'0'+h:h; var m = (m<10)?'0'+m:m; var s = (s<10)?'0'+s:s; //拼装字符串 var dateStr = "距离世界末日还有 "+h+':'+m+':'+s; //赋值 document.getElementById('box').innerHTML = dateStr; //判断 if (seconds <= 0) { document.getElementById('box').innerHTML = "让地球重生吧！"; return; } //时间减少 seconds --; //定时 setTimeout(runTime, 1000); } </script> </body> </html>