javascript set cookie with expire time

I've set the time to 1000*36000.

function display() { 
  var now = new Date();
  var time = now.getTime();
  var expireTime = time + 1000*36000;
  now.setTime(expireTime);
  document.cookie = 'cookie=ok;expires='+now.toUTCString()+';path=/';
  //console.log(document.cookie);  // 'Wed, 31 Oct 2012 08:50:17 UTC'
}

Below are code snippets to create and delete a cookie. The cookie is set for 1 day.

// 1 Day = 24 Hrs = 24*60*60 = 86400.

1. By using max-age:

   • Creating the cookie:

   document.cookie = "cookieName=cookieValue; max-age=86400; path=/;";
   

   • Deleting the cookie:

   document.cookie = "cookieName=; max-age=- (any digit); path=/;";
   

2. By using expires:

   • Syntax for creating the cookie for one day:

   var expires = (new Date(Date.now()+ 86400*1000)).toUTCString();
   document.cookie = "cookieName=cookieValue; expires=" + expires + 86400) + ";path=/;"
   

Here's a function I wrote another application. Feel free to reuse:

function writeCookie (key, value, days) {
    var date = new Date();

    // Default at 365 days.
    days = days || 365;

    // Get unix milliseconds at current time plus number of days
    date.setTime(+ date + (days * 86400000)); //24 * 60 * 60 * 1000

    window.document.cookie = key + "=" + value + "; expires=" + date.toGMTString() + "; path=/";

    return value;
};