cookie 读取

/** *@name cookie的名字 */function getCookie(name) {     var prefix = name + "="     var start = document.cookie.indexOf(prefix)     if (start==-1) {         return null;     }         var end = document.cookie.indexOf(";", start+prefix.length)     if (end==-1) {         end=document.cookie.length;     }     var value=document.cookie.substring(start+prefix.length, end)     return value; }