Question: I have two arrays and I would like to compare if these arrays have duplicated values, then return the values that aren't duplicates. Based on these two arrays I would like to return the string `Eucalipto`.

```js
const plants = [
  {
    id: 59,
    kind: "Cana-de-açucar"
  },
  {
    id: 60,
    kind: "Citros"
  }
];

const auxPlants = [
  "Cana-de-açucar",
  "Citros",
  "Eucalipto"
]
```

Answer: 
You can use `Array#map` to find all the `kind` values, pass that to the `Set` constructor, and then use `Array#filter` to find all elements of the array not in that `Set`.

```js
const plants = [
  {
    id: 59,
    kind: "Cana-de-açucar"
  },
  {
    id: 60,
    kind: "Citros"
  }
];
const auxPlants = [
  "Cana-de-açucar",
  "Citros",
  "Eucalipto"
];
const set = new Set(plants.map(({kind})=>kind));
const res = auxPlants.filter(x => !set.has(x));
console.log(res);
```
sounds like you want to filter the array of values you're interested in based on if they're not found in the other array, like so:

```
const nonDuplicates = auxPlants.filter(a => !plants.find(p => p.kind === a))

```

it's unclear if you'd also want values from the `plants` array that are non duplicate as well, or if you're only interested in uniques from the `auxPlants` array