Diff two arrays - intermediate algorithm scripting

Compare two arrays and return a new array with any items only found in one of the two given arrays, but not both. In other words, return the symmetric difference of the two arrays.

Note: You can return the array with its elements in any order.

function diffArray(arr1, arr2) {
  let newArr = arr1.concat(arr2);

  return newArr.filter(char => {
    return arr1.indexOf(char) === -1 || arr2.indexOf(char) === -1;
  });
}

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