How to join .map and .filter to filter and remove duplicate in object array?
I currently have to use two variables for this:
const arrayOne = [
{
id: 1,
name: "João",
city: {
id: 1,
name: "Rio de Janeiro"
}
},
{
id: 1,
name: "Pedro",
city: {
id: 2,
name: "Salvador"
}
},
{
id: 1,
name: "Tiago",
city: {
id: 1,
name: "Rio de Janeiro"
}
}
];
const arrayTwo = arrayOne.map(function (item, index) {
return item.city;
});
const arrayThree = arrayTwo.filter(
(elem, index, arr) => index === arr.findIndex((t) => t.id === elem.id)
);
Just chain them together?
const result = arrayOne.map(function (item, index) {
return item.city;
}).filter(
(elem, index, arr) => index === arr.findIndex((t) => t.id === elem.id)
);
If you mean that you want to map and filter at the same time, then you can use either flatMap or reduce as described in another Q/A: https://stackoverflow.com/a/34398349/211627
If your filter is just to remove duplicates consider creating a Map which simply overwrites all duplicate city.ids. This can then be converted back to an array, here using spread syntax on the Map.values().
const arrayOne = [
{ id: 1, name: 'João', city: { id: 1, name: 'Rio de Janeiro' } },
{ id: 1, name: 'Pedro', city: { id: 2, name: 'Salvador' } },
{ id: 1, name: 'Tiago', city: { id: 1, name: 'Rio de Janeiro' } },
];
const arrayTwo = [...new Map(arrayOne.map(({ city }) => [city.id, city])).values()];
console.log(arrayTwo);