Run results for: Delete vs set undefined Properties

Run details:

User agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:91.0) Gecko/20100101 Firefox/91.0

Browser: Firefox 91

Operating system: Ubuntu

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
Deleted	10861958.0 Ops/sec
Set undefined	3435383.0 Ops/sec
Iterate deleted	103988336.0 Ops/sec
Iterate set undefined	40494232.0 Ops/sec

Script Preparation code:

var objA = {a:1, b:2, c:3, d:4};
var objB = {a:1, b:2, c:3, d:4};
delete objA.a;
delete objA.b;
delete objA.c;
delete objA.d;
objB.a = undefined;
objB.b = undefined;
objB.c = undefined;
objB.d = undefined;

function doNothing(objin){}

Tests:

Deleted
Object.entries(objA);
Set undefined
Object.entries(objB);
Iterate deleted
for(let a in objA) doNothing(a)
Iterate set undefined
for(let b in objB) doNothing(b)

Run results for: Delete vs set undefined Properties

Deleted

Set undefined

Iterate deleted

Iterate set undefined