1function setCookie(name,value,days) {
2    var expires = "";
3    if (days) {
4        var date = new Date();
5        date.setTime(date.getTime() + (days*24*60*60*1000));
6        expires = "; expires=" + date.toUTCString();
7    }
8    document.cookie = name + "=" + (value || "")  + expires + "; path=/";
9}
10function getCookie(name) {
11    var nameEQ = name + "=";
12    var ca = document.cookie.split(';');
13    for(var i=0;i < ca.length;i++) {
14        var c = ca[i];
15        while (c.charAt(0)==' ') c = c.substring(1,c.length);
16        if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
17    }
18    return null;
19}
20
21setCookie("user_email","bobthegreat@gmail.com",30); //set "user_email" cookie, expires in 30 days
22var userEmail=getCookie("user_email");//"bobthegreat@gmail.com"

1const getCookie = (cookie_name) =>{
2  // Construct a RegExp object as to include the variable name
3  const re = new RegExp(`(?<=${cookie_name}=)[^;]*`);
4  try{
5    return document.cookie.match(re)[0];	// Will raise TypeError if cookie is not found
6  }catch{
7    return "this-cookie-doesn't-exist";
8  }
9}
10
11getCookie('csrftoken')	// ADZlxZaPSa6k4oyelVBa5iWTtLJW8P3Jf7nhW90L2ZWc5Zcq2vKLO1RRFbaKco3C
12getCookie('_non_existent') // this-cookie-doesn't-exist
13

1
2function setCookie(cname, cvalue, exdays = 999) {
3  const d = new Date();
4  d.setTime(d.getTime() + exdays * 24 * 60 * 60 * 1000);
5  const expires = 'expires=' + d.toUTCString();
6  document.cookie = cname + '=' + cvalue + ';' + expires + ';path=/';
7}
8
9function getCookie(cname) {
10  const cookies = Object.fromEntries(
11    document.cookie.split(/; /).map(c => {
12      const [key, v] = c.split('=', 2);
13      return [key, decodeURIComponent(v)];
14    }),
15  );
16  return cookies[cname] || '';
17}
18
19setCookie('language', 'vietnam', 365);
20var userEmail = getCookie('language');

1function getCookie(cookie, name) {
2  const q = {}
3  cookie?.replace(/\s/g, '')
4    .split(';')
5    .map(i=>i.split('='))
6    .forEach(([key, value]) => {
7      q[key] = value
8    })
9  return q[name]??null;
10}

1function setCookie(cname, cvalue, exdays=999) {
2  var d = new Date();
3  d.setTime(d.getTime() + (exdays * 24 * 60 * 60 * 1000));
4  var expires = "expires="+d.toUTCString();
5  document.cookie = cname + "=" + cvalue + ";" + expires + ";path=/";
6}
7
8function getCookie(cname) {
9  var name = cname + "=";
10  var ca = document.cookie.split(';');
11  for(var i = 0; i < ca.length; i++) {
12    var c = ca[i];
13    while (c.charAt(0) == ' ') {
14      c = c.substring(1);
15    }
16    if (c.indexOf(name) == 0) {
17      return c.substring(name.length, c.length);
18    }
19  }
20  return "";
21}

1For storing array inside cookie : 
2-----------------------------------
3setter : var json_str = JSON.stringify(arr); cookie.set('mycookie', json_str);
4getter : cookie.get('mycookie'); var arr = JSON.parse(json_str);
5----------------------------------------------------------------------------
6Function common for all type of variable : 
7==========================================
8let cookie = {
9            set: function(name, value) {
10                document.cookie = name+"="+value;
11            },
12            get: function(name) {
13                let nameEQ = name + "=";
14                let ca = document.cookie.split(';');
15                for( let i = 0; i < ca.length; i++ ) {
16                    let c = ca[i];
17                    while (c.charAt(0)==' ') c = c.substring(1,c.length);
18                    if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
19                }
20                return null;
21            }
22        }