Why is this not working

Tell us what’s happening:
I don’t know why the code is not returning anything and is returning an empty array. I’ve seen this code inside a function and it works but I don’t get why?

The code inside a function working:

'function diffArray(arr1, arr2) {
var newArr = [ ];

function onlyInFirst(first, second) {
// Looping through an array to find elements that don’t exist in another array
for (var i = 0; i < first.length; i++) {
if (second.indexOf(first[i]) === -1) {
// Pushing the elements unique to first to newArr
newArr.push(first[i]);
}
}
}

onlyInFirst(arr1, arr2);
onlyInFirst(arr2, arr1);

return newArr;
}’

Your code so far


function diffArray(arr1, arr2) {
var newArr = [];
for(let i = 0; i < arr1.length;i++){
  if(arr2.indexOf(arr1[i])===-1){
    newArr.push(arr1[i])
  }
} return newArr
}

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

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Challenge: Diff Two Arrays

Link to the challenge: