用一个一分钟的倒计时，倒计时完了后能显示出一个按钮javascript做

<div id="pad"></div>
<button id="btn" style="display:none;">xxx</button><script>
var n = 10
var tid = setTimeout("show()", 100);function show(){
   if(tid != null) {clearTimeout(tid);tid = null;}
   if(n==0) document.getElementById("btn").style.display = "block";
   else{n--;document.getElementById("pad").innerText = n;tid = setTimeout("show()", 100);}
}
</script>

解决方案 »

  1.   

    <body></body>
    <script>
    var i=60;
    function $(Id){return document.getElementById(Id)}
    function create(elm,parent,fn){
    var obj = document.createElement(elm)
        if(fn)fn(obj)
    parent.appendChild(obj)
    }
    create('div',document.body,function(obj){obj.id='show';})
    var timer = setInterval(function(){
    if(i==0){clearTimeout(timer);create("input",document.body,function(obj){obj.type="button";obj.value='hi!!'})}
    $('show').innerHTML=i;
    i--;
    },1000)
    </script>
      

  2.   

    cookie + setTimeout
    (按钮:type=submit)
      

  3.   

    <body></body>
    <script>
    var i=60*15;
    function $(Id){return document.getElementById(Id)}
    function create(elm,parent,fn){
        var obj = document.createElement(elm)
        if(fn)fn(obj)
        parent.appendChild(obj)
    }
    create('div',document.body,function(obj){obj.id='show';})
    var timer =setInterval(function(){
    var rs=/time=\w+/.exec(document.cookie);
    if(rs==null)
    {
    document.cookie="time="+i;
    $('show').innerHTML=i;
    }
    else
    {
        var num = parseInt(/\d+/.exec(rs.toString()));
    if(num!=0)
    {
    num--;
    $('show').innerHTML=num;
    document.cookie="time="+num
            }
    else
    {
     clearTimeout(timer);
     var   d   =   new   Date(2000,1,1); 
     document.cookie   ="time=;expires= " + d.toGMTString()  //清除cookie
     create("input",document.body,function(obj){obj.type="submit";obj.value='hi!!'})
     //alert(document.cookie)
    }
    }
    },1)//改成1000
    </script>