js获取指定的cookie的具体实现

var cookieName = "cookie名字"; 
var cookieValue = null;//返回cookie的value值 
if (document.cookie && document.cookie != '') { 
var cookies = document.cookie.split(';');//将获得的所有cookie切割成数组 
for (var i = 0; i < cookies.length; i++) { 
var cookie = cookies[i];//得到某下标的cookies数组 
if (cookie.substring(0, cookieName.length + 2).trim() == cookieName.trim() + "=") {//如果存在该cookie的话就将cookie的值拿出来 
cookieValue = cookie.substring(cookieName.length + 2, cookie.length); 
break 
} 
} 
} 
if (cookieValue != "" && cookieValue != null) {//如果存在指定的cookie值 
alert(cookieValue); 
} else {<span style="font-family: Arial, Helvetica, sans-serif;">//如果cookie的值是空</span> 
alert("not cookie!!!"); 
}

//去除空格 
String.prototype.trim = function () { 
return this.replace(new RegExp("(^[\\s]*)|([\\s]*$)", "g"), ""); 
}