Benchmark: Object vs Map - creation with dynamic keys

Object vs Map - creation with dynamic keys (version: 1)

Explores performance of different ways to build a data structure with a dynamic set of keys that we know up front.

Comparing performance of: Empty Map + loop insert - creation vs Map constructor - creation vs Object with eval hack - creation vs Empty Map + loop insert - lookup vs Map constructor - lookup vs Eval hack - lookup vs Empty object - creation vs Empty object - lookup

Created: 2 months ago by: Registered User

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HTML Preparation code:

<!--your preparation HTML code goes here-->

Script Preparation code:

const keys = new Array(100);
for(let i = 0; i < 100; i++) {
  keys[i] = Math.random().toString(36).slice(2); 
}

const lookupKeys = new Array(500);
for(let i = 0; i < 500; i++) {
  lookupKeys[i] = Math.random() < 0.2 ? keys[Math.floor(Math.random() * 100)] : Math.random().toString(36).slice(2);
}

Tests:

Empty Map + loop insert - creation
const map = new Map(); for(let i = 0, keyLen = keys.length; i < keyLen; i++) { map.set(keys[i], true); }
Map constructor - creation
const map = new Map(keys.map((k) => [k, true]));
Object with eval hack - creation
const obj = eval(`({ ${keys.map((k) => `"${k}": true`).join(", ")} })`);
Empty Map + loop insert - lookup
const map = new Map(); for(let i = 0, keyLen = keys.length; i < keyLen; i++) { map.set(keys[i], true); } let hits = 0; for(const k of lookupKeys) { if(map.get(k)) { hits++; } }
Map constructor - lookup
const map = new Map(keys.map((k) => [k, true])); let hits = 0; for(const k of lookupKeys) { if(map.get(k)) { hits++; } }
Eval hack - lookup
const obj = eval(`({ ${keys.map((k) => `"${k}": true`).join(", ")} })`); let hits = 0; for(const k of lookupKeys) { if(obj[k]) { hits++; } }
Empty object - creation
const obj = {}; for(let i = 0, keyLen = keys.length; i < keyLen; i++) { obj[keys[i]] = true; }
Empty object - lookup
const obj = {}; for(let i = 0, keyLen = keys.length; i < keyLen; i++) { obj[keys[i]] = true; } let hits = 0; for(const k of lookupKeys) { if(obj[k]) { hits++; } }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Empty Map + loop insert - creation
Map constructor - creation
Object with eval hack - creation
Empty Map + loop insert - lookup
Map constructor - lookup
Eval hack - lookup
Empty object - creation
Empty object - lookup

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:147.0) Gecko/20100101 Firefox/147.0

Browser/OS: Firefox 147 on Windows

View result in a separate tab

Test name	Executions per second
Empty Map + loop insert - creation	154122.1 Ops/sec
Map constructor - creation	157437.2 Ops/sec
Object with eval hack - creation	93488.7 Ops/sec
Empty Map + loop insert - lookup	38848.7 Ops/sec
Map constructor - lookup	38870.0 Ops/sec
Eval hack - lookup	11985.6 Ops/sec
Empty object - creation	148925.1 Ops/sec
Empty object - lookup	28887.2 Ops/sec