Intermediate Algorithm Scripting: Sorted Union help

What is wrong?

function uniteUnique(...arr) {
  let newArr = [];
  let ret = [];
  let x;
  for (let i = 1; i < arr.length; i++){
    x = 0;
    newArr = arr[i].filter((a) => {
      if ((a !== 1)  && (a !== 2) && (a !== 3)){
        return a;
    if (x > 0){
  return ret;

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

I’ve edited your post for readability. When you enter a code block into a forum post, please precede it with a separate line of three backticks and follow it with a separate line of three backticks to make easier to read.

Note: Backticks are not single quotes.

See this post to find the backtick on your keyboard. The “preformatted text” tool in the editor (</>) will also add backticks around text.


You need to review how filter works: you don’t return a value from it, you return true or false and it returns a new array keeping things that are true.

I can see what you’re trying to do though, and you’re literally checking if the value is not 1, 2 or 3. The point is to do a union of any collection of arrays, not just the one for that specific test. The tests are there as a baseline to make sure your code works, you can’t hardcode the answers to one specific test and expect to pass