Run results for: Undefined vs null

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/133.0.0.0 Safari/537.36

Browser: Chrome 133

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
setting null	43529.4 Ops/sec
setting undefined	44489.4 Ops/sec

Script Preparation code:

function ctor() {
 	var obj = { a: { a: 5 }, b: { b: 5 }, c: { c: 6 }, d: 5, e: [Math.random(), Math.random()] }; 
  	return obj;
}

Tests:

setting null
var objects = []; for (var i = 0; i < 1000; i++) { objects[i] = ctor(); } var obj = objects[Math.floor(Math.random() * 1000)]; window.leak = obj.a + obj.b + obj.c + obj.d + obj.e; for (var i = 0; i < 1000; i++) { obj.a = null; obj.b = null; obj.c = null; obj.d = null; obj.e = null; }
setting undefined
var objects = []; for (var i = 0; i < 1000; i++) { objects[i] = ctor(); } var obj = objects[Math.floor(Math.random() * 1000)]; window.leak = obj.a + obj.b + obj.c + obj.d + obj.e; for (var i = 0; i < 1000; i++) { obj.a = void 0; obj.b = void 0; obj.c = void 0; obj.d = void 0; obj.e = void 0; }