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

JavaScript already has reverse() method on Array, so you don't need to do that much!

Imagine you have the array below:

var arr = [1, 2, 3, 4, 5];

Now simply just do this:

arr.reverse();

and you get this as the result:

[5, 4, 3, 2, 1];

But this basically change the original array, you can write a function and use it to return a new array instead, something like this:

function reverse(arr) {
  var i = arr.length, reversed = [];
  while(i) {
    i--;
    reversed.push(arr[i]);
  }
  return reversed;
}

Or simply chaning JavaScript built-in methods for Array like this:

function reverse(arr) {
  return arr.slice().reverse();
}

and you can call it like this:

reverse(arr); //return [5, 4, 3, 2, 1];

Just as mentioned, the main difference is in the second way, you don't touch the original array...