创建一个轮询器,每隔X毫秒将cookie值与先前已知的值进行比较.

// basic functions from the excellent http://www.quirksmode.org/js/cookies.html
function readCookie(name) {
    var nameEQ = name + "=";
    var ca = document.cookie.split(';');
    for(var i=0;i < ca.length;i++) {
        var c = ca[i];
        while (c.charAt(0)==' ') c = c.substring(1,c.length);
        if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
    }
    return null;
}

/////////////////////////////////
// ACTUAL FUN STUFF BELOW
/////////////////////////////////

var cookieRegistry = [];

function listenCookieChange(cookieName,callback) {
    setInterval(function() {
        if (cookieRegistry[cookieName]) {
            if (readCookie(cookieName) != cookieRegistry[cookieName]) { 
                // update registry so we dont get triggered again
                cookieRegistry[cookieName] = readCookie(cookieName); 
                return callback();
            } 
        } else {
            cookieRegistry[cookieName] = readCookie(cookieName);
        }
    },100);
}

用法将是这样的：

listenCookieChange('foo',function() {
    alert('cookie foo has changed!');
});

注意：这尚未经过测试,只是我将如何解决问题的快速演示.

编辑：我现在测试了它,它的工作原理. See example