js 弹出 隐藏层和cookie

<script type="text/javascript">

function checkCookie(show_div, bg_div) {
var smtstk = getCookie('smtstk');
if (smtstk == "no" ||smtstk=="") {//如果有cookie则不再展示
//document.getElementById("tstk").style.display = "none";
ShowDiv(show_div, bg_div);
}
else {
//document.getElementById("tstk").style.display = "block";
CloseDiv(show_div, bg_div);
}
}

//弹出隐藏层
function ShowDiv(show_div, bg_div) { //ShowDiv('MyDiv','fade')
document.getElementById(show_div).style.display = 'block';
document.getElementById(bg_div).style.display = 'block';
var bgdiv = document.getElementById(bg_div);
bgdiv.style.width = document.body.scrollWidth;
$("#" + bg_div).height($(document).height());
document.body.style.overflow = "hidden";

};
//关闭弹出层
function CloseDiv(show_div, bg_div) {
setCookie("smtstk", "no");
document.getElementById(show_div).style.display = 'none';
document.getElementById(bg_div).style.display = 'none';
document.body.style.overflow = "scroll";
};

//读取cookie
function getCookie(cname) {
var name = cname + "=";
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);
if (c.indexOf(name) != -1) return c.substring(name.length, c.length);
}
return "";
}

//设置cookie
function setCookie(cname, cvalue) {
document.cookie = cname + "=" + cvalue + "";
}
</script>