Intermediate Algorithm Scripting: Diff Two Arrays - freeCodeCamp solution

sol.js

function diffArray(arr1, arr2) {
  let newArr1 = arr1.filter(val => {
    return arr2.indexOf(val) == -1;
  })
  let newArr2 = arr2.filter(val => {
    return arr1.indexOf(val) == -1;
  })
  return newArr1.concat(newArr2);
}