Javascript Cookie代码未存储Cookie/读取空Cookie值

我从Headfirst Javascript书中获取了这段代码，用于cookie。但由于某些原因，它无法与我的浏览器配合使用。我主要使用chrome和ff，并且我在chrome中启用了本地cookie。帮助

<script type="text/javascript">

function checkCookie(){
    var name = eatCookie("yahooEmail");
    if(name)
        document.getElementById("emailVerf").style.visibility="hidden";
    else
        document.getElementById("emailBody").style.visibility="hidden";
}

function writeCookie(name, val, days){
    var expires = "";
    if(days){
        var date = new Date();
        date.setTime(date.getTime + (days * 24 * 60 * 60 * 1000));
        expires = "; expires=" + date.toGMTString();
    }
    document.cookie = name + "=" + val + expires + "; path=/";
}
function eatCookie(val){
    var search = val + "=";
    var cookies = document.cookie.split(';');
    for(var i=0; i < cookies.length; i++){
        var c = cookies[i];
        while(c.charAt(0) == ' ')
            c=c.substring(1, c.length);
        if(c.indexOf(search) == 0)
            return c.substring(search.length, c.length);
    }
    return null;
}
function verEmail(val){
    var regex = "[a-zA-Z0-9][@yahoo.com]";
    var exp = new RegExp(regex);
    if(!exp.test(val)){
        document.getElementById("email").style.color="red";
        alert("Please enter a valid Yahoo email address.");
        }
    else{
        writeCookie("yahooEmail", val, 7);
        document.getElementById("emailVerf").style.visibility="hidden";
        document.getElementById("emailBody").style.visibility="visible";
        }
}
</script>