Run results for: Object, Map: string vs numeric smi keys access performance

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.164 Safari/537.36 Edg/91.0.864.71

Browser: Chrome 91

Operating system: Windows

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
Object random string keys	206.8 Ops/sec
Object random numeric smi keys	209.6 Ops/sec
Object sequential string keys	228.5 Ops/sec
Object sequential numeric smi keys	222.6 Ops/sec
Map random string keys	209.3 Ops/sec
Map random numeric smi keys	218.4 Ops/sec
Map sequential string keys	210.4 Ops/sec
Map sequential numeric smi keys	212.1 Ops/sec

Script Preparation code:

function shuffleArray(array) {
    for (let i = array.length - 1; i > 0; i--) {
        const j = Math.floor(Math.random() * (i + 1));
        [array[i], array[j]] = [array[j], array[i]];
    }
}

// 31 bit +ve integer smi
var randSmi = () => crypto.getRandomValues(new Uint32Array(1))[0] & 0x7fffffff;
// 6-7 char alphanumeric string
var randStr = () => randSmi().toString(36);

var numEntries = 64;
var numRounds = 100 * numEntries;

var strObj = {};
var strObjKeys = Array(numEntries);
var numObj = {};
var numObjKeys = Array(numEntries);

var strSeqObj = {};
var strSeqObjKeys = Array(numEntries);
var numSeqObj = {};
var numSeqObjKeys = Array(numEntries);

for (let i = 0; i < numEntries; i++) {
let strKey = `k${randStr()}`, numKey = randSmi();
let strSeqKey = `k${i}`, numSeqKey = i;
	strObj[strKey] = i;
	strObjKeys[i] = strKey;
	numObj[numKey] = i;
	numObjKeys[i] = numKey;

	strSeqObj[strSeqKey] = i;
	strSeqObjKeys[i] = strSeqKey;
	numSeqObj[numSeqKey] = i;
	numSeqObjKeys[i] = numSeqKey;
}

Object.freeze(strObj);
Object.freeze(numObj);
Object.freeze(strSeqObj);
Object.freeze(numSeqObj);

var strMap = new Map(Object.entries(strObj));
var numMap = new Map(Object.entries(numObj));
var strSeqMap = new Map(Object.entries(strSeqObj));
var numSeqMap = new Map(Object.entries(numSeqObj));

Tests:

Object random string keys
let total = 0; for (let i = 0; i < numRounds; i++) { total += strObj[strObjKeys[Math.random() * numEntries | 0]]; }
Object random numeric smi keys
let total = 0; for (let i = 0; i < numRounds; i++) { total += numObj[numObjKeys[Math.random() * numEntries | 0]]; }
Object sequential string keys
let total = 0; for (let i = 0; i < numRounds; i++) { total += strSeqObj[strSeqObjKeys[Math.random() * numEntries | 0]]; }
Object sequential numeric smi keys
let total = 0; for (let i = 0; i < numRounds; i++) { total += numSeqObj[numSeqObjKeys[Math.random() * numEntries | 0]]; }
Map random string keys
let total = 0; for (let i = 0; i < numRounds; i++) { total += strMap.get(strObjKeys[Math.random() * numEntries | 0]); }
Map random numeric smi keys
let total = 0; for (let i = 0; i < numRounds; i++) { total += numMap.get(numObjKeys[Math.random() * numEntries | 0]); }
Map sequential string keys
let total = 0; for (let i = 0; i < numRounds; i++) { total += strSeqMap.get(strSeqObjKeys[Math.random() * numEntries | 0]); }
Map sequential numeric smi keys
let total = 0; for (let i = 0; i < numRounds; i++) { total += numSeqMap.get(numSeqObjKeys[Math.random() * numEntries | 0]); }

Run results for: Object, Map: string vs numeric smi keys access performance

For small ~ 64 entry constant tables

Object random string keys

Object random numeric smi keys

Object sequential string keys

Object sequential numeric smi keys

Map random string keys

Map random numeric smi keys

Map sequential string keys

Map sequential numeric smi keys