Run results for: reduce vs for to mapify array

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/12.0.2 Safari/605.1.15

Browser: Safari 12

Operating system: Mac OS X 10.14.2

Device Platform: Desktop

Date tested: 5 years ago

Test name	Executions per second
reduce	35.4 Ops/sec
for	5512.1 Ops/sec

Script Preparation code:

var arr = [];

for(i=0; i<500; i++){
  arr.push({
    id: Math.random().toString(36).slice(2),
    other_data: {}
  });
}

Tests:

reduce
var mapped_reduce = arr.reduce((acc,val) => { return {...acc,[val.id]:val} },{})
for
var mapped_for = {}; for (let i = 0; i < arr.length; i++) { mapped_for[arr[i].id] = arr[i]; }