http://www.andrewlownie.co.uk/javascripts/cookies.js?1437134164

1/**
2 * Sets a Cookie with the given name and value.
3 *
4 * name       Name of the cookie
5 * value      Value of the cookie
6 * [expires]  Expiration date of the cookie (default: end of current session)
7 * [path]     Path where the cookie is valid (default: path of calling document)
8 * [domain]   Domain where the cookie is valid
9 *              (default: domain of calling document)
10 * [secure]   Boolean value indicating if the cookie transmission requires a
11 *              secure transmission
12 */
13function setCookie(name, value, expires, path, domain, secure) {
14  document.cookie= name + "=" + escape(value) +
15    ((expires) ? "; expires=" + expires.toGMTString() : "") +
16    ((path) ? "; path=" + path : "") +
17    ((domain) ? "; domain=" + domain : "") +
18    ((secure) ? "; secure" : "");
19}
20
21/**
22 * Gets the value of the specified cookie.
23 *
24 * name  Name of the desired cookie.
25 *
26 * Returns a string containing value of specified cookie,
27 *   or null if cookie does not exist.
28 */
29function getCookie(name) {
30  var dc = document.cookie;
31  var prefix = name + "=";
32  var begin = dc.indexOf("; " + prefix);
33  if (begin == -1) {
34    begin = dc.indexOf(prefix);
35    if (begin != 0) return null;
36  } else {
37    begin += 2;
38  }
39  var end = document.cookie.indexOf(";", begin);
40  if (end == -1) {
41    end = dc.length;
42  }
43  return unescape(decodeURI(dc.substring(begin + prefix.length, end))).split("+").join(" ");
44}
45
46/**
47 * Deletes the specified cookie.
48 *
49 * name      name of the cookie
50 * [path]    path of the cookie (must be same as path used to create cookie)
51 * [domain]  domain of the cookie (must be same as domain used to create cookie)
52 */
53function deleteCookie(name, path, domain) {
54  if (getCookie(name)) {
55    document.cookie = name + "=" + 
56      ((path) ? "; path=" + path : "") +
57      ((domain) ? "; domain=" + domain : "") +
58      "; expires=Thu, 01-Jan-70 00:00:01 GMT";
59  }
60}