Run results for: mutate-vs-map

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:109.0) Gecko/20100101 Firefox/119.0

Browser: Firefox 119

Operating system: Mac OS X 10.15

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
for of	34940.9 Ops/sec
map	34092.4 Ops/sec

Script Preparation code:

var arr = [];
for (var i = 0; i < 1000; i++) {
    arr[i] = {
        name: `${i}`,
        value: i
    };
}

function someFn(i) {
    const x24 = i.value * 3 * 8;
    i.value = x24;
    i.name = `${x24}`;
    return i;
}

​x
 
var arr = [];for (var i = 0; i < 1000; i++) {    arr[i] = {        name: `${i}`,        value: i    };}​function someFn(i) {    const x24 = i.value * 3 * 8;    i.value = x24;    i.name = `${x24}`;    return i;}

Tests:

for of
for (var y of arr) { someFn(y); }
for (var y of arr) {
someFn(y);
}
map
arr.map(item => someFn(item))
arr.map(item => someFn(item))

Run results for: mutate-vs-map

for of

map