How can I reverse an array in JavaScript without using libraries?

Question

I am saving some data in order using arrays, and I want to add a function that the user can reverse the list. I can\'t think of any possible method, so if anybo

Answer 1

Pure functions to reverse an array using functional programming:

var a = [3,5,7,8];

// ES2015
function immutableReverse(arr) {
  return [ ...a ].reverse();
}

// ES5
function immutableReverse(arr) {
  return a.concat().reverse()
}