五.点击发送验证码小demo

<input type="button" id="send" value="发送验证码">

    window.onload=function(){
        var send=document.getElementById('send'),
            times=60, 
            timer=null;
        send.onclick=function(){
          // 计时开始 
         timer=setInterval(function(){
             times--;
             if(times<=0){
                 send.value="发送验证码";
                 clearInterval(timer);
                 times=10;
                 send.disabled=false;
             }else{
                 send.value=times+"秒后重试"
                 send.disabled=true;
             }
         },1000)
        } 
    }