Run results for: foreach vs filter+map

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.113 Safari/537.36

Browser: Chrome 60

Operating system: Mac OS X 10.12.6

Device Platform: Other

Date tested: 6 years ago

Test name	Executions per second
filter + map	419800.5 Ops/sec
forEach	490936.4 Ops/sec

Script Preparation code:

var contacts = {
  'a1@a.com': {id: 1},
  'a2@a.com': {id: 2},
  'a3@a.com': {id: 3},
  'a4@a.com': {id: 4},
  'a5@a.com': {id: 5},
  'a6@a.com': {id: 6},
  'a7@a.com': {id: 7},
  'a8@a.com': {id: 8},
  'a9@a.com': {id: 9},
  'a10@a.com': {id: 10},
}

var selectedItems = [1,3,7];

Tests:

filter + map
Object.values(contacts).map(contact => contact.id).filter(id => selectedItems.indexOf(id) === -1)
forEach
Object.values(contacts).forEach((contact) => { if (selectedItems.indexOf(contact.id) === -1) { selectedItems.push(contact.id); } });

Run results for: foreach vs filter+map

filter + map

forEach