原文地址：http://www.oschina.net/code/snippet_2001568_48311
特別說(shuō)明：cookie最初創(chuàng)建的有效時(shí)間是60秒。也就是說(shuō)景用，你如果在倒計(jì)時(shí)為20的時(shí)候坦胶，關(guān)閉網(wǎng)頁(yè).20秒之后再打開(kāi)叔扼，是不會(huì)有倒計(jì)時(shí)顯示的街氢；但是突诬，如果倒計(jì)時(shí)為20時(shí)苫拍，關(guān)閉頁(yè)面，如果在20秒內(nèi)重新打開(kāi)頁(yè)面旺隙，是有倒計(jì)時(shí)顯示的绒极。

CSS：

.inp_number{ width: 200px; height: 30px;}
.sendBtn{ width: 120px; height: 35px; background: #4b8ccb; border: none; color: #FFF; cursor: pointer;}
.gray{ background: #c5c5c5; }

HTML：

<div class="message_send">
    <input type="text" class="inp_number"/>
    <input type="button" value="發(fā)送驗(yàn)證碼" class="sendBtn" id="send"/>
</div>

JS：

$(function(){
    $('#send').click({function(){
        sendCode($("#send"));
    });
    v = getCookieValue("secondsremained") ? getCookieValue("secondsremained") : 0; //獲取cookie值
    if(v>0){
        settime($("#send"));//開(kāi)始倒計(jì)時(shí)
    }
}
//發(fā)送驗(yàn)證碼
function sendCode(obj){
    var phoneNum = $('.inp_number').val();
    var resule = isPhoneNum();
    if(result){
        // doPostBack(url,backFunc1,{"phoneNum":phonenum});
        addCookie("secondsremained",60,60); //添加cookie記錄，有效時(shí)間為60s
        settime(obj); //開(kāi)始倒計(jì)時(shí)
    }
}
//將手機(jī)利用ajax提交到后臺(tái)的發(fā)短信接口
function doPostBack(url,backFunc,queryParam){
    $.ajax({
        async : false,
        cache : false,
        type : 'POST',
        url : url, //請(qǐng)求的action路徑
        data : queryParam,
        error : function(){
             //請(qǐng)求失敗處理函數(shù)
        }
        success : backFunc
    });
}
function backFunc1(data){
    var d = $.parseJSON(data);
    if(!d.success){
        alert(d.msg);
    }else{
        //返回驗(yàn)證碼
        alert("模擬驗(yàn)證碼：" + d.msg);
        $("#code").val(d.msg);
    }
}
//發(fā)送驗(yàn)證碼是添加cookie
function addCookie(name,value,expirseHours){
    var cookieString = name + "=" + escape(value);
    //判斷是否設(shè)置過(guò)期時(shí)間蔬捷，0代表關(guān)閉瀏覽器時(shí)失效
    if(expiresHours > 0){
        var date = new Date();
        date.setTime(date.getTime() + expiresHours * 1000);
        cookieString = cookieString + ";expires=" + date.toUTCString();
    }
    document.cookie = cookieString;
}
//修改cookie的值
function editCookie(name,value,expiresHours){
    var cookieString = name + "=" + escape(value);
    if(expiresHours > 0){
        var date = new Date();
        date.setTime(date.getTime() + expiresHours * 1000);
        cookieString = cookieString + ";expires=" + date.toUTCString();
    }
    document.cookie = cookieString;
}
//根據(jù)名字獲取cookie的值
function getCookieValue(name){
    var strCookie = document.cookie;
    var arrCookie = strCookie.split("; ");
    for(var i=0; i < arrCookie.length; i++){
        var arr = arrCookie[i].split("=");
        if(arr[0] == name){
            return unescape(arr[1]);
            break;
        }
    }
}
//倒計(jì)時(shí)
var countdown;
function settime(obj){
    countdown =  getCookieValue("secondsremained");
    if(countdown == 0){
        obj.removeAttr("disabled");
        obj.val("免費(fèi)獲取驗(yàn)證碼");
        return;
    }else{
        obj.attr("disabled" , true);
        obj.val("重新發(fā)送（" + countdown + "）" );
        countdown--;
        editCookie("secondsremained", countdown, countdown+1);
    }
    setTimeout(function(){
        settime(obj)
    },1000); //每1000秒執(zhí)行一次
}
//驗(yàn)證手機(jī)號(hào)碼是否合法
function isPhoneNum(){
    var phoneNum = $('.inp_number').val();
    var myreg = /^(((13[0-9]{1})|(15[0-9]{1})|(18[0-9]{1}))+\d{8})$/;
    if(phoneNum == '' || !myreg.test(phoneNum)){
        alert('請(qǐng)輸入正確的手機(jī)號(hào)碼垄提！');
        return false;
    }else{
        return false;
    }
}