<!DOCTYPE html> <html> <head> <title>作业</title> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <style type="text/css"> input { width: 300px; text-align: center; } </style> <script type="text/javascript"> var hour = 0; var minute = 0; var second = 0; var interval; var flag = true; window.onload = function() { //当按钮点击时 document.getElementById("btn").onclick = function() { this.disabled = "disabled"; //time(); interval = window.setInterval("time()", 1000); }; //对暂停继续按钮进行注册事件 document.getElementById("btn1").onclick = function() { if (flag) { window.clearInterval(interval); } else { interval = window.setInterval("time()", 1000); } flag=!flag; }; } var time = function() { second++; if (second >= 60) { minute++; second = 0; } if (minute >= 60) { minute = 0; hour++; } hour = parseInt(hour) > 9 ? hour : "0" + parseInt(hour); minute = parseInt(minute) > 9 ? minute : "0" + parseInt(minute); second = parseInt(second) > 9 ? second : "0" + parseInt(second); document.getElementById("txt").value = hour + ":" + minute + ":" + second; //让上面的代码，每间隔一秒钟执行一次. //setTimeout("time()", 1000); } </script> </head> <body> <input type="text" id="txt" readonly="readonly"> <br> <input type="button" value="开始" id="btn"> <br> <input type="button" value="暂停/继续" id="btn1"> </body> </html>