Run results for: Map vs Object with 100 keys and 1/2 delete

Run details:

User agent: Mozilla/5.0 (Windows NT 6.2; Win64; x64) AppleWebKit/604.1.38 (KHTML, like Gecko) Chrome/49.0.2623 Safari/604.1.38 CoherentGT/2.0

Browser: Chrome 49

Operating system: Windows 8

Device Platform: Desktop

Date tested: 10 months ago

Obj set

4K/s

Map set

3K/s

View exact numbers

Test name	Executions per second
✓ Obj set	3,777 Ops/sec
Map set	3,412 Ops/sec

Script Preparation code:

var map = new Map();
var obj = {};

const nbKeys = 100;
for(let n =0; n<nbKeys; n++)
{
  const nKey = n;
  const nValue = Math.random();
  map.set(nKey, nValue );
  obj[nKey] = nValue ;
}
var i = 0, count = 1000, a;
function getRandomInt(max) {
  return Math.floor(Math.random() * max);
}

const deleteFreq = 2;

Tests:

Map set
for (i = 0; i < count; i++) { const deleteOrSet = getRandomInt(deleteFreq) !== 0 if(deleteOrSet) map.delete(getRandomInt(nbKeys)); else map.set(getRandomInt(nbKeys), getRandomInt(42)); }
Obj set
for (i = 0; i < count; i++) { const deleteOrSet = getRandomInt(deleteFreq) !== 0 if(deleteOrSet) delete obj[getRandomInt(nbKeys)]; else obj[getRandomInt(nbKeys)] = getRandomInt(42); }

Run results for: Map vs Object with 100 keys and 1/2 delete

Lookup of map vs object

Map set

Obj set