Run results for: map foreach vs array lookup vs map const of vs arr const of

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/94.0.4606.20 Safari/537.36 Edg/94.0.992.4

Browser: Chrome 94

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
arr to map lookup	421.8 Ops/sec
map foreach	11167.0 Ops/sec
map const of	17877.6 Ops/sec
arr const of	178679.2 Ops/sec

Script Preparation code:

var arr = [];
var map = new Map();

for (let i = 0; i < 12000; i++) {
  const num = i * 7 + Math.ceil(Math.random() * 5); 
  const str = (Math.random() + 1).toString(36).substring(7);
  arr.push(num);
  map.set(num, str);
}

Tests:

arr to map lookup
for (let i = 0;i < arr.length; i++) { let num = arr[i]; let str = map.get(num) || ''; }
map foreach
map.forEach((el)=>{})
map const of
for (const str of map) { let str32 = str[1]}
arr const of
for (const str of arr) { let str32 = str}

Run results for: map foreach vs array lookup vs map const of vs arr const of

arr to map lookup

map foreach

map const of

arr const of