Perfomance difference between looping an array using Array methods and simple boring for loop

performance-comparison-loop-array-with-for-and-array-methods-node.js

'use strict';

var i, tmp, initTime, stopTime;
var arr = Array(99999999);

// Iterate using `for` loop
tmp = 0;
initTime = Date.now();
for (i = 0; i < arr.length; i++) {
  tmp += i;
}
stopTime = Date.now();

console.log('Iterate using boring `for` loop: %s ms', stopTime - initTime);

// Iterate using reduce and declaring function straightaway in the reduce function call
tmp = 0;
initTime = Date.now();
tmp = arr.reduce(function (prev, curr, i) {
  return prev + i;
}, tmp);
stopTime = Date.now();

console.log('Iterate using Array.reduce with function declaration into the function call: %s ms', stopTime - initTime);

// Iterate using reduce but declaring function outside and passing the reference to reduce
function reduceFn (prev, curr, i) {
  return prev + i;
}

tmp = 0;
initTime = Date.now();
tmp = arr.reduce(reduceFn, tmp);
stopTime = Date.now();

console.log('Iterate using Array.reduce with function declaration outside the function call: %s ms', stopTime - initTime);

// Iterate using forEach and declaring function straightaway in the reduce function call
tmp = 0;
initTime = Date.now();
arr.forEach(function (value, i) {
  tmp += i;
});
stopTime = Date.now();

console.log('Iterate using Array.forEach with function declaration into the function call: %s ms', stopTime - initTime);

// Iterate using forEach but declaring function outside and passing the reference to reduce
function forEachFn (val, i) {
  tmp += i;
}

tmp = 0;
initTime = Date.now();
arr.forEach(forEachFn);
stopTime = Date.now();

console.log('Iterate using Array.forEach with function declaration outside the function call: %s ms', stopTime - initTime);