Diff Two Arrays - Help

JavaScript
1

I’m not sure why this won’t work.

Your code so far

function diffArray(arr1, arr2) {
  var newArr = [];
  // Same, same; but different.
  var arr = arr1.concat(arr2);
  
  for(var i = 0; i < arr.length; i++){
    if(arr.indexOf(arr[i]) == -1){
      newArr.push(arr[i]);
    }
  }
  
  return newArr;
}

diffArray([1, 2, 3, 5], [1, 2, 3, 4, 5]);

Your browser information:

Your Browser User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.139 Safari/537.36.

Link to the challenge:
https://www.freecodecamp.org/challenges/diff-two-arrays

3

As the men above said: Concat is superfluous. You need two loops. One to compare using indexOf, first array elements to another, other loop to compare second array elements to first array. Inside ifs just chuck it into array that need to be returned.