Performance Comparison of reduce+spread vs reduce+Object.Assign

spread_vs_objectAssign.js

const arrOfMaps = new Array(40000).fill(0).map((k,i) => {
    return { [i]:`testdsfsdfdsfsdfsdfsdf${i}`};
})

console.time('functional')
const finalMap = arrOfMaps.reduce((acc, current) => ({ ...acc, ...current }), {});
console.log('finalMap keys', Object.keys(finalMap).length);
console.timeEnd('functional')

console.time('object assign')
const finalMapAssign = arrOfMaps.reduce((acc, current) => {
    return Object.assign(acc, current);
}, {});
console.log('object assign keys', Object.keys(finalMapAssign).length);
console.timeEnd('object assign') // this will be 150X faster because no intermediate objects are created after each iteration