Mutations: Array.lenght not working

Hello, everyone,

I need some advice with this challenge.
I am hacking at it bit by bit as I usually do, using console.log within the function to test if the output is getting me closer.

The problem is that even that is not working.
I have added a “console.log(arr2.lenght);” and its output is blank, literally.

As you can see in the code, there are 2 console.log testers.
Currently the output is exactly this:

A blank space followed by false on the next row.

What am I doing wrong here?

Thank you!

Your code so far

function mutation(arr) {

  var counter = 0;

  let arr1 = arr[0].toLowerCase().split('');
  let arr2 = arr[1].toLowerCase().split('');

  for (var i = 0; i < arr2.lenght; i++) {
    if (arr1.includes(arr2[i]) == true) {
      counter += 1;

  if (counter == arr2.lenght) {
    return true;
  return false;


console.log(mutation(["Hello", "hey"]));

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36.

Link to the challenge:

You have a spelling error