Run results for: The fastest way to iterate over arrays

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_6) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/14.0.3 Safari/605.1.15

Browser: Safari 14

Operating system: Mac OS X 10.15.6

Device Platform: Desktop

Date tested: 2 years ago

Script Preparation code:

var objectSize = 1000000;
var iterations = 20;

var array = [];

for (var i = 0; i < objectSize; i++) {
    array[i] = `val${i}`;
}

Tests:

for loop
for (var i = 0; i < iterations; i++) { for (var key = 0; key < array.length; key++) { var k = array[key]; } }
for loop with length caching
for (var i = 0; i < iterations; i++) { var length = array.length; for (var key = 0; key < length; key++) { var k = array[key]; } }
for...of
for (var i = 0; i < iterations; i++) { for (var value of array) { var k = value; } }
for...in
for (var i = 0; i < iterations; i++) { for (var key in array) { var k = array[key]; } }
forEach
for (var i = 0; i < iterations; i++) { array.forEach((value) => { var k = value; }); }
map
for (var i = 0; i < iterations; i++) { array.map((value) => { var k = value; }); }