var date = new Date(); 
date.setTime(date.getTime() + (x * 60 * 1000)); 
$.cookie('example', 'foo', { expires: date }); 

<script type="text/javascript">
var expiresDate= new Date();
expiresDate.setTime(expire.getTime() + ("__cookie__", 'helloworld', {
      path : '/',      //cookie的作用域
      expires : expiresDate
    });
}
</script>

function SetCookie(name,value){
 var str=name+"="+escape(value);
 var dd = new Date(); 
 dd.setDate(dd.getDate()+1);//获取明天 
 var y = dd.getYear(); 
 var m = dd.getMonth()+1;//获取当前月份的日期
 var d = dd.getDate(); 
 date = new Date(y+'-'+m+'-'+d+' 00:00:00');
 date.setTime(date.getTime());//明天的0:00:00
 str+=";expires="+date.toGMTString();
 document.cookie = str;
 }