commo.js

function setCookie(name, value) {    var Days = 30;    var exp = new Date();    exp.setTime(exp.getTime() + Days * 24 * 60 * 60 * 1000);    document.cookie = name + "=" + escape(value) + ";expires=" + exp.toGMTString();}function getCookie(name) {    var arr, reg = new RegExp("(^| )" + name + "=([^;]*)(;|$)");    if (arr = document.cookie.match(reg))        return unescape(arr[2]);    else        return null;}function delCookie(name) {    var exp = new Date();    exp.setTime(exp.getTime() - 1);    var cval = getCookie(name);    if (cval != null)        document.cookie = name + "=" + cval + ";expires=" + exp.toGMTString();}function checkCookie() {    if (getCookie("userName") == null || getCookie("roleName") == null) {        alert("未登录!");        window.location.href = "login.jsp";    }}function clearCookie() {    delCookie("userName");    delCookie("roleName");    window.location.href = "login.jsp";}

实例

setCookie("userName","xxx");

 注：cookie中不能存放一些标点符号，所以使用unescape解码，escape编码，使某些标点符号合法。