js cookie设置最大过期时间 Infinity

<script>

//cookie 
function addCookie(objName,objValue,objDays){
var str = objName + "=" + escape(objValue);
console.log(Infinity);   //Infinity
console.log(typeof Infinity);   //number
console.log(Infinity.constructor); //function Number() { [native code] }
if(objDays > 0){
var date = new Date();
var ms = objDays*24*3600*1000;
date.setTime(date.getTime() + ms);
str += "; expires=" + date.toGMTString();
}
if(objDays===Infinity){
  str += "; expires=Fri, 31 Dec 9999 23:59:59 GMT";
}

str += "; path=/";
document.cookie = str;
};



 var itemtitle=document.querySelector(".item-title");
 document.querySelector(".sava_cookie").addEventListener("click",function(e){
	   var putCookieVal=itemtitle.innerHTML;
	   addCookie(‘surface‘,putCookieVal,Infinity);
	 
 });
  

</script>