Run results for: undefined vs. typeof vs. in vs. hasOwnProperty vs wrapped function

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.100 Safari/537.36

Browser: Chrome 69

Operating system: Mac OS X 10.14.0

Device Platform: Desktop

Date tested: 5 years ago

Test name	Executions per second
undefined	4099815.0 Ops/sec
typeof	13604450.0 Ops/sec
in	12387070.0 Ops/sec
hasOwnProperty	12082220.0 Ops/sec
truthy	13510320.0 Ops/sec
local undef	6803485.0 Ops/sec
isDefined	7115531.0 Ops/sec

Script Preparation code:

var obj = { a: 1, b: 2, c: 3, d: 4, e: 5 };
var undef;

function isDefined (o) {
    return typeof o !== "undefined";
}

const isDefined2 = (o) => {
    return typeof o !== "undefined";
}

const isDefined3 = (o) => typeof o !== "undefined";


const Sys = {
	isDefined (o) {
    	return typeof o !== "undefined";
	}

}

Tests:

undefined
undefined !== obj.d;
typeof
'undefined' !== typeof obj.d;
in
'd' in obj;
hasOwnProperty
obj.hasOwnProperty( 'd' );
truthy
!! obj.d;
local undef
undef !== obj.d;
isDefined
isDefined(obj.d)

Run results for: undefined vs. typeof vs. in vs. hasOwnProperty vs wrapped function

Object lookup performance

undefined

typeof

in

hasOwnProperty

truthy

local undef

isDefined