How can JS set the validity period of cookie to 24 o'clock on the same day and pop up the welcome login interface

Simply write, according to the specified parameters Deadline format time for testing, if there are some imprecise place also please point out.

//  Settings cookie Expires at the specified time point of the day and prompts 
function setCookie(name,value,Deadline,callback){
//  Gets the current date object 
var curDate = new Date();
//  Gets the timestamp corresponding to the current date 
var curTime = curDate.getTime();
//  Gets the timestamp of the specified time 
var endTime = convertTime(curDate,Deadline);
//  Calculates the time difference between the specified time and the current time 
var disTime = endTime - curTime;
//  Settings cookie Expired time 
document.setCookie = name + '=' + value + ';expires=' + disTime;
//  Executes a callback after the specified time has arrived 
setTimeout(callback,disTime);
}
setCookie('name','value','24:00:00',function(){
alert('cookie Expired ');
});
//  Gets the timestamp of the specified time 
function convertTime(nowDate,Deadline){
//  Partition parameter Deadline
var _dateArr = Deadline.split(':');
//  Get the corresponding hours, minutes and seconds in the parameters respectively 
var hours = parseInt(_dateArr[0]);
var minutes = parseInt(_dateArr[1]);
var seconds = parseInt(_dateArr[2]);
//  Set the corresponding time and second 
nowDate.setHours(hours); 
nowDate.setMinutes(minutes); 
nowDate.setSeconds(seconds);
//  Gets the number of milliseconds corresponding to the specified time division and second in the current day 
var result = Date.parse(nowDate);
return result;
}

Additional:

function setCookie(name,value,days){// Settings cookie
var d = new Date();
d.setTime(d.getTime() + (days*24*60*60*1000));
var expires = "expires="+d.toUTCString();
document.cookie = name + "=" + value + "; " + expires;
}