// JavaScript Document
/********************************************************************
主题:Cookies操作
作者:Issac
日期:Sep.2005
说明:
	问题:Mozilla下尚不支持若干方法.
********************************************************************/

//读取Cookie
function readCookie(cookieName){
	var cookieString = document.cookie;
	var start = cookieString.indexOf(cookieName + '=');
	//加上等号的原因是避免在某些Cookie的值里有与cookieName一样的字符串

	if (start == -1) // 找不到

		return null;
	start += cookieName.length + 1;
	var end = cookieString.indexOf(';', start);
	if (end == -1)
		return unescape(cookieString.substring(start));
	return unescape(cookieString.substring(start, end));
}
//写入Cookie(其中expiresTime,expiresTimeUnit可缺省)
function writeCookie(cookieName, cookieValue, expiresTime, expiresTimeUnit){
	if (expiresTime > 0){
		var expires = new Date();
		switch (expiresTimeUnit) {
			case "y":
			case "Y":
				expires.setTime(expires.getTime() + expiresTime * 365 * 24 * 60 * 60 * 1000);
				break;
			case "m":
			case "M":
				expires.setTime(expires.getTime() + expiresTime * 30 * 24 * 60 * 60 * 1000);
				break;
			case "d":
			case "D":
				expires.setTime(expires.getTime() + expiresTime * 24 * 60 * 60 * 1000);
				break;
			case "h":
			case "H":
				expires.setTime(expires.getTime() + expiresTime * 60 * 60 * 1000);
				break;
			case "min":
			case "MIN":
				expires.setTime(expires.getTime() + expiresTime * 60 * 1000);
				break;
			case "s":
			case "S":
				expires.setTime(expires.getTime() + expiresTime * 1000);
				break;
			default:
				expires.setTime(expires.getTime() + expiresTime * 24 * 60 * 60 * 1000);
				break;
		}
		document.cookie = cookieName+"="+escape(cookieValue)+";expires=" + expires.toGMTString();
	}
	else if (expiresTime < 0)
		delCookie(cookieName);
	else
		document.cookie = cookieName+"="+escape(cookieValue);
}
//删除Cookie
function delCookie(cookieName){
	var expires = new Date();
	expires.setTime(expires.getTime() - 1);
	document.cookie = cookieName+"=Issac;expires=" + expires.toGMTString();
}