Run results for: isArray2

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.75 Safari/537.36

Browser: Chrome 86

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
Array.isArray	7212452.0 Ops/sec
Is Undefined	3775461.0 Ops/sec
Is Undefined (fail)	3784531.0 Ops/sec

Script Preparation code:

var array = [
    [1, 2, 3],
    [1, 2, 3], undefined, [1, 2, 3]
]

function isDefined(obj) {
    return obj !== undefined
}
var isArray = Array.isArray

Tests:

Array.isArray
isArray(array[2])
Is Undefined
isDefined(array[2])
Is Undefined (fail)
isDefined(array[3])

Array.isArray vs Object.prototype.toString vs [].constructor vs instanceof

Array.isArray

Is Undefined

Is Undefined (fail)