function setCookie(name,value,limitDay) {
try{
var Days =parseInt(limitDay);
var exp = new Date();
exp.setTime(exp.getTime() + Days*24*60*60*1000);
document.cookie = name + "="+ escape (value) + ";expires=" + exp.toGMTString();
}catch(e){
//alert("something wrong when set cookie.");
}
}