Run results for: reduce collection

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.132 Safari/537.36

Browser: Chrome 76

Operating system: Linux

Device Platform: Desktop

Date tested: 4 years ago

Test name	Executions per second
mutate reducer 1	1395.8 Ops/sec
mutate reducer 2	1093.4 Ops/sec
mutate reducer 3	1436.2 Ops/sec
shallow copy reducer	46.5 Ops/sec

Script Preparation code:

var collection = Array(10000).fill().map(() => ({ 
  section: { id: 'id_' + ~~(Math.random()*10) }, 
  user: { id: 'id_' + ~~(Math.random()*10) },  
}))

Tests:

mutate reducer 1
var result = collection.reduce((acc, { section, user }) => { if (!acc[section.id]) { acc[section.id] = [user.id]; return acc; } acc[section.id].push(user.id); return acc; }, {});
mutate reducer 2
var result = collection.reduce((acc, { section, user }) => { acc[section.id] = acc[section.id] || []; acc[section.id].push(user.id); return acc; }, {});
mutate reducer 3
var result = collection.reduce((acc, { section, user }) => { if (!acc[section.id]) { acc[section.id] = []; } acc[section.id].push(user.id); return acc; }, {});
shallow copy reducer
var result = collection.reduce((acc, { section, user }) => ({ ...acc, [section.id]: [...(acc[section.id] || []), user.id] }), {});

Run results for: reduce collection

some reducer over collection test

mutate reducer 1

mutate reducer 2

mutate reducer 3

shallow copy reducer