Stuck in javascript list-ops

Programming JavaScript
1

Hi,

I’m stuck in the first task and I notice the same kind of feedback popping up in task 2. I suspect I don’t really understand what I’m asked to to. There is one test I’m just not passing in task one and for the life of me, I can’t say why.

These are the instructions:

append (given two lists, add all items in the second list to the end of the first list);

This is the test:

  test('non-empty lists', () => {
    const list1 = new List([1, 2]);
    const list2 = new List([2, 3, 4, 5]);
    expect(list1.append(list2).values).toEqual([1, 2, 2, 3, 4, 5]);
  });

Here’s the code: I’m passing the first three conditions with no problem but I’m just not able to pass the last one.

  append(list2) {
    if(this.list != undefined && list2.list === undefined) {
      return this;
    }
    else if(this.list === undefined && list2.list === undefined) {
      return new List();
    }
    else if(this.list === undefined && list2.list != undefined) {
      return list2;
    }
    else if(this.list != undefined && list2.list != undefined) {
      this.list.push(...list2.list);
      return this.list;   // logs as [1, 2, 2, 3, 4, 5]
    }
  }

The problem lies in the last conditional.
And this is what I get as result

    Expected: [1, 2, 2, 3, 4, 5]
    Received: [Function values]

Function values ? I don’t get it. When I log this.list I can see the array I’m supposed to return and I’m returning this.list. I’ve also tried with a for-loop and push(). Nothing works. What is that I’m not getting ?

I’ve been at it for days now. Any help is welcome.

Thanks and greetings,
Karin

2

The test expects you to return the custom List object, not an Array. Note the test is checking the the .values property on the returned object.

3

I don’t get it. I can return this and I get undefined.
I can set it equal to a new array called newList and return new List(newList). I get undefined.

I don’t understand this at all.

4

The tests expect List.values to be defined. How do you define that property?

5

Please share your whole code. I’m particularly interested to see your constructor.

6

I got it. I hadn’t looked at the constructor and I had wondered about values but I thought it was some syntax that belonged to the test. I hadn’t seen that it was actually a clue.

Thank you very much.

7

I got it. Thanks for the clue. I had not looked at that constructor.

Thank you very much.