Run results for: Array push vs spread concat'''

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/105.0.0.0 Safari/537.36

Browser: Chrome 105

Operating system: Windows

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
Spread and map	39321.8 Ops/sec
Simple for loop	24846.8 Ops/sec

Script Preparation code:

var arr1 = [];
var person = {
    name: 'John',
    lastname: 'Doe',
};
for (let i = 0; i < 30; i++) {
    arr1.push(person);
}
var arr2 = [];
for (let i = 30; i < 60; i++) {
    arr2.push(person);
}

Tests:

Spread and map
var result = [ ...(arr1.map(x => ({ ...person, id: '1' }))), ...(arr2.map(x => ({ ...person, id: '1' }))), ];
Simple for loop
var resul2 = []; for (let item of arr1) { resul2.push({ ...person, id: '1' }); } for (let item of arr2) { resul2.push({ ...person, id: '1' }); }

Run results for: Array push vs spread concat'''

Spread and map

Simple for loop