Run results for: undefined vs typeof vs in vs hasOwnProperty

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/92.0.4495.0 Safari/537.36

Browser: Chrome 92

Operating system: Windows

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
undefined	1045.1 Ops/sec
typeof	1458.2 Ops/sec
in	2764.5 Ops/sec
hasOwnProperty	1736.8 Ops/sec
bool	1442.7 Ops/sec

Script Preparation code:

var obj = { a: 1, b: 2, c: 3, d: 4, e: 5 };
var keys = new Array(4096 * 5);
for (let i = 0; i < keys.length; i += 1)
  keys[i] = Math.random().toString();

Tests:

undefined
for (let i = 0; i < 4096; i += 1) obj[keys[4096 * 0 + i]] === undefined;
typeof
for (let i = 0; i < 4096; i += 1) typeof obj[keys[4096 * 1 + i]] === "undefined";
in
for (let i = 0; i < 4096; i += 1) keys[4096 * 2 + i] in obj;
hasOwnProperty
for (let i = 0; i < 4096; i += 1) obj.hasOwnProperty(keys[4096 * 3 + i]);
bool
for (let i = 0; i < 4096; i += 1) !obj[keys[4096 * 4 + i]];

Run results for: undefined vs typeof vs in vs hasOwnProperty

Object lookup performance

undefined

typeof

in

hasOwnProperty

bool