Intermediate Algorithm Scripting code not working

JavaScript
1

Challenge link

I realize how clunky this code is, but I’m not entirely sure why it’s not working. Logging destroyer([1, 2, 3, 1, 2, 3], 2, 3) returns [1, 3, 1] rather than [1, 1] like it’s intended to. Any help would be appreciated.

function destroyer(arr) {
  let args = [...arguments];
  let newArr = [];
  for (e = 1; e < (args.length - 1); e++) {
    let target = args[e];
    for (f = 0; f < (arr.length - 1); f++) {
      let arrEl = arr[f]
      if (arr[f] !== target) {
        newArr.push(arrEl);
      }
    }
    return newArr;
  }
}

console.log(destroyer([1, 2, 3, 1, 2, 3], 2, 3));
2

Thing 1: You are using < (arr.length -1) which will stop without hitting the last item in the array. You usually want to either use < arr.length or <= (arr.length - 1).

Thing 2: You are returning newArr inside your loop. That means that you only ever check one value.

Thing 3: You are adding to newArr as you go, but never removing anything from it. If you fix the problems above, you’ll still get incorrect answers because first you will add all the values that are not 2 (including 3s) then you will add the values that are not 3 (including 2) and you will add some values multiple times.

3

I tried starting over from the beginning here:

function destroyer(arr) {
  let args = [...arguments];
  args.shift();

  for (i = 0; i < args.length; i++) {
    for (f = 0; f < arr.length; f++) {
      var newArr = arr.filter(el => el !== args[i]);
    }
  }
  
  return newArr;
}

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

It looks like it’s still only checking one value, even though I’m returning newArr outside the loop this time.

4

You are replacing newArr every time the inner loop runs, so at the end of the function only has the last value filtered out.

5

I managed to solve it using splice(). Probably not the most elegant solution, but it works.

Thanks so much for the help. This was super frustrating.

function destroyer(arr) {
  let newArr = arr;
  let args = [...arguments];
  args.shift();

  for (i = 0; i < args.length; i++) {
    for (f = 0; f < newArr.length; f++) {
      while (newArr[f] === args[i]) {
        newArr.splice(f, 1);
      }
    }
  }

  return newArr;
}

console.log(destroyer([1, 2, 3, 1, 2, 3], 2, 3));