JS工具类的一个详细介绍，如何操作Cookie

/***
	*读取指定的Cookie值 readCookie("id");
	*@param {string} cookieName Cookie名称
	*/
	function readCookie(cookieName) {
	    var theCookie = "" + document.cookie;
	    var ind = theCookie.indexOf(cookieName);
	    if(ind==-1 || cookieName=="") return "";
	    var ind1 = theCookie.indexOf(';',ind);
	    if(ind1==-1) ind1 = theCookie.length;
	    /*读取Cookie值*/
	    return unescape(theCookie.substring(ind+cookieName.length+1,ind1));
	}
	
	/***
	* 设置Cookie值 setCookie("id",1);
	* @param {string} cookieName Cookie名称
	* @param {string} cookieValue Cookie值
	* @param {number} nDays Cookie过期天数
	*/
	function setCookie(cookieName, cookieValue) {
	    /*当前日期*/
	    var today = new Date();
	    /*Cookie过期时间*/
	    var expire = new Date();
	    /*如果未设置nDays参数或者nDays为0，取默认值1*/
	    //if(nDays == null || nDays == 0) nDays = 1;
	    /*计算Cookie过期时间【 3600000 * 24  为一天】*/
	    expire.setTime(today.getTime() + 400000); //5分钟
	    document.cookie = cookieName + "=" + escape(cookieValue) + ";expires=" +      expire.toGMTString();
	}
	
	/***
	* 删除cookie中指定变量函数  
	* @param {string} $name Cookie名称
	*/    
    function deleteCookie($name){    
         var myDate=new Date();    
         myDate.setTime(-1000);//设置时间    
         document.cookie=$name+"=''; expires="+myDate.toGMTString();                
    }
	
	/***
	* 删除cookie中所有定变量函数  
	* @param {string} cookieName Cookie名称
	* @param {string} cookieValue Cookie值
	* @param {number} nDays Cookie过期天数
	*/  
    function clearCookie(){    
         var myDate=new Date();    
         myDate.setTime(-1000);//设置时间    
         var data=document.cookie;    
         var dataArray=data.split("; ");    
         for(var i=0;i<dataArray.length;i++){    
              var varName=dataArray[i].split("=");    
              document.cookie=varName[0]+"=''; expires="+myDate.toGMTString();    
         }    
    }