Efficient Way of Filtering Array and Mapping in ES6

Question

I wanted to get array that have status of "Existing" only and don't add the status in the newArray. What is the most efficient way of doing this?

const products = [
    {
        "id": "111",
        "name": "grapes",
        "status": "Linked",
    },
    {
        "id": "222",
        "name": "banana",
        "status": "Existing",
    },
    {
        "id": "333",
        "name": "mango",
        "status": "Existing",
    },
    {
      "id": "444",
      "name": "salad",
      "status": "Linked",
      
    },
    {
        "id": "555",
        "name": "juice",
        "status": "Existing",
    }
]

  const newArray = 
    products?.map(({ name = '', id = '' }) => ({
      name,
      id,
    }))

Answer 1

I think the problem is that you are trying to do both in one array function. I would filter it by status === "Existing" using filter , then map it, removing the status property.

 const products = [{ "id": "111", "name": "grapes", "status": "Linked", }, { "id": "222", "name": "banana", "status": "Existing", }, { "id": "333", "name": "mango", "status": "Existing", }, { "id": "444", "name": "salad", "status": "Linked", }, { "id": "555", "name": "juice", "status": "Existing", } ] const newArray = products.filter((elem) => elem.status === "Existing").map(({ id, name, status }) => ({ id, name })) console.log(newArray);

Answer 2

The most efficient in terms of lines of code is probably just a filter() followed by a map() operation:

const result = products.filter(({status}) => status === 'Existing')
                       .map(({id, name}) => ({id, name}));

---

Full snippet:

 const products = [{ "id": "111", "name": "grapes", "status": "Linked", }, { "id": "222", "name": "banana", "status": "Existing", }, { "id": "333", "name": "mango", "status": "Existing", }, { "id": "444", "name": "salad", "status": "Linked", }, { "id": "555", "name": "juice", "status": "Existing", }]; const result = products.filter(({status}) => status === 'Existing').map(({id, name}) => ({id, name})); console.log(result);

Since that requires a double iteration, the most efficient in terms of performance will probably be an explicit for loop that pushes matching values into a result array.

If you want to do everything in a single iteration but still maintain a functional approach, you could do everything with one reduce() operation:

 const products = [{ "id": "111", "name": "grapes", "status": "Linked", }, { "id": "222", "name": "banana", "status": "Existing", }, { "id": "333", "name": "mango", "status": "Existing", }, { "id": "444", "name": "salad", "status": "Linked", }, { "id": "555", "name": "juice", "status": "Existing", }]; const result = products.reduce((a, {id, name, status}) => { if (status === 'Existing') a.push({id, name}); return a; }, []); console.log(result);