js实现点击注册按钮开始读秒倒计时的小例子

js

<script language="javascript"> 
<!-- 
var wait_time = 8; //设置秒数(单位秒) 
var secs_time = 0;          
for(var i=1;i<=wait_time;i++) 
{ 
 window.setTimeout("sTimer("+i+")",i*1000); 
} 
function sTimer(num) 
{ 
 if(num==wait_time) 
 { 
  document.getElementById("reg_btn").value=" 同意注册 "; 
  document.getElementById("reg_btn").disabled=false; 
 } 
 else 
 { 
  secs_time=wait_time-num; 
  document.getElementById("reg_btn").value="请先阅读服务条款 ("+secs_time+")"; 
 } 
} 
//--> 
</script>

html

<div style="width:350px; text-align:center;"> 
<form name="regForm" method="post" action=""> 
<input type="submit" value="请先阅读服务条款 (0)" disabled="disabled" id="reg_btn"> 
<input id="BtnClose" type="button" value=" 我不同意 " onclick="window.close();"> 
</form> 
</div>