Run results for: Test samples

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.143 Safari/537.36

Browser: Chrome 53

Operating system: Mac OS X 10.11.5

Device Platform: Other

Date tested: 8 years ago

Test name	Executions per second
Old method	2773775.0 Ops/sec
New check	825094.9 Ops/sec
New replace	539295.2 Ops/sec

Script Preparation code:

var domEl = document.createElement("span"), cls = " aaaaaaaaaaaaaaaaaaaaaa  bbbbbbbbbbbbbbbbb ", _hasCls = function(domEl, cls) {
			var found	= false,
				pos		= domEl.className.indexOf(cls);

			if (pos >= 0) {
				var endpos = pos + cls.length;
				found = endpos == domEl.className.length || domEl.className.charAt(endpos) == ' ';
			}

			return found;
		};

Tests:

Old method
if (!_hasCls(domEl, cls)) { if (domEl.className.length > 0) { cls = ' ' + cls; } domEl.className += cls; }
New check
cls.split(' ').forEach(function(onecls) { if (onecls) domEl.classList.add(onecls); });
New replace
cls.replace(/\s+/g, ' ').trim().split(' ').forEach(function(onecls) { domEl.classList.add(onecls); });

Run results for: Test samples

Test

Old method

New check

New replace