js-array-reverse-bmark.js

// simple benchmark for reversing a string in js - source https://medium.com/quick-code/5-ways-to-reverse-a-string-in-javascript-466f62845827
function reverseFor(str){
  let reversed = "";    
  for (var i = str.length - 1; i >= 0; i--){        
    reversed += str[i];
  }    
  return reversed;
}
function reverseArray(str){
  return str.split("").reverse().join("");
}
function reverseSpread(str){
  return [...str].reverse().join('');
}
function reverseReduce(str){
  return str.split("").reduce((rev, char)=> char + rev, ''); 
}
function reverserecursion(str){
 if(str === ""){
  return str 
 }else{
  return reverserecursion(str.substr(1)) + str[0]
 }
}

let string = 'hello world'
let iterations = 100000
let bmarkData = [
	{
		'function': reverseFor,
		'name': 'reverseFor',
		'time': 0
	},
	{
		'function': reverseArray,
		'name': 'reverseArray',
		'time': 0
	},
	{
		'function': reverseSpread,
		'name': 'reverseSpread',
		'time': 0
	},
	{
		'function': reverseReduce,
		'name': 'reverseReduce',
		'time': 0
	},
	{
		'function': reverserecursion,
		'name': 'reverserecursion',
		'time': 0
	},
]
bmarkData.forEach((data) => {
	let before = Date.now()
	for (let i = 0; i < iterations; i++) {
		data.function(string)
	}
	let after = Date.now()
	data.time = (after - before)
})

console.log(bmarkData)

Here's the numbers I got on an i7 laptop; time is milliseconds for 1 million iterations. Timing is closer than I would have expected, but as you might expect, reverseFor is the winner.

• name: 'reverseFor', time: 235
• name: 'reverseArray', time: 677
• name: 'reverseSpread', time: 750
• name: 'reverseReduce', time: 262
• name: 'reverserecursion',time: 420

Test string is pretty short, so I replaced it with the comment from the first line of the script. Again, time is milliseconds for 1 million iterations. Surprisingly, reverseReduce wins this time.

• name: 'reverseFor', time: 2144
• name: 'reverseArray', time: 4821
• name: 'reverseSpread', time: 6643
• name: 'reverseReduce', time: 1893
• name: 'reverserecursion',time: 5514

Now we just need an analysis of memory usage for these.