Run results for: Diffenent ways to get cookie

Test name	Executions per second
✓ LastIndexOf	1,489,296 Ops/sec
LastindexOf2	895,242 Ops/sec
Original	745,671 Ops/sec
Regex	657,166 Ops/sec
RegexLoop	543,653 Ops/sec

Script Preparation code:

function getCookieIX(name,str){
  name = name+'=';
  var ck = str || document.cookie;
  var idx = ck.lastIndexOf(name);
  if(idx==-1){ return undefined}
  var nameLength = name.length;
  var p1 = ck.substring(idx+nameLength);
  var idx2 = p1.indexOf(';');
  if(idx2>-1){
    p1 = p1.substring(0,idx2);
  }
  return p1;
}

function getCookieIX2(name, str) {
  name = name + "=";
  var ck = str || document.cookie;
  ck = "; " + ck;
  // support if the 
  var ckLC = ck.toLowerCase();
  var idx = ckLC.lastIndexOf("; " + name.toLowerCase());
  if (idx == -1) {
    return undefined;
  }
  var nameLength = name.length;
  var p1 = ck.substring(idx + nameLength);
  var idx2 = p1.indexOf(";");
  if (idx2 > -1) {
    p1 = p1.substring(0, idx2);
    p1 = decodeURIComponent(p1);
    return p1;
  }
  return p1;
}

function getCookie(name) {
  var nameEQ = name + "=";
  var ca = document.cookie.split(";");
  for (var i = 0; i < ca.length; i++) {
    var c = ca[i];
    while (c.charAt(0) == " ") c = c.substring(1, c.length);
    if (c.indexOf(nameEQ) == 0) {
      var d = c.substring(nameEQ.length, c.length);
      d = decodeURIComponent(d);
      return d;
    }
  }
  return undefined;
}

function getCookieM(name) {
  name = name + "";
  var re = new RegExp("(^| )" + name + "=([^;]+)", "gmi");
  var m = document.cookie.match(re);
  if (!!m) {
    m = m.pop();
    m = m.substring(m.indexOf("=") + 1);
    m = !!m ? decodeURIComponent(m) : m;
    return m;
  }
}

function getCookieW(name, str) {
  var str = str || document.cookie;
  var re = new RegExp("(?:^|; )("+name+"+?)(?:=([^;]*))?(?:;|$)", "gi");
  var value;
  var match;
  while ((match = re.exec(str))) {
    re.lastIndex = match.index + match.length - 1;
    var k = match[1];
    var v = decodeURIComponent(match[2]);
    !!v && (value = v);
  }

  return value;
}

document.cookie = "foo=bar";
document.cookie = "foo=nope;domain=measurethat.net";

Run results for: Diffenent ways to get cookie

Original

Regex

RegexLoop

LastIndexOf

LastindexOf2