Map object if property is found in another array of objects

Question

This is my case.

data: [
    {
      q: "question 1",
      a: "answer 1"
    }, 
    {
      q: "question 2"
    }
]

How can I map this into key: value pair so that the final output is { "question 1": "answer 1"}?

The trick is that only if a property exists then it should be assigned to the new object as above example { "question N": "answer N"}.

I have tried combining .map() and .filter(), but it didn't work.

For example:

const obj = data.map(e => e.q).filter(s => s.a)

Thanks.

Answer 1

You need to filter element first and then map

let data = [{q: "question 1",a: "answer 1"},{q: "question 2"}]

const obj = data.filter(s => s.a)
                .map(({q,a}) => ({ [q]: a }))

console.log(obj)

---

Can we get output as object, you can use reduce and build an Object,

let data = [{q: "question 1",a: "answer 1"},{q: "question 2"}]

const obj = data.reduce((op,{q,a})=>{
  if( a ) op[q] = a
  return op
},{})

console.log(obj)

---

In modern browser you can Object.fromEntries too

let data = [{q: "question 1",a: "answer 1"},{q: "question 2"}]

const obj = Object.fromEntries(data.filter(s => s.a)
                .map(({q,a}) => [q,a]))

console.log(obj)

Answer 2

You can use map() and then filter().

let data = [{ q: "question 1", a: "answer 1" }, { q: "question 2" } ];

let result = data.map(item => {
  if (item.q && item.a) {
    return {
      [item.q]: item.a
    };
  }
}).filter(item => item); // Filter undefined values.

console.log(result);

Answer 3

For a single object, you could take Object.fromEntries for creating a sigle object out of key/value pairs.

var data = [{ q: "question 1", a: "answer 1" }, { q: "question 2" }],
    result = Object.fromEntries(data
        .map(({ q, a }) => [q, a])
        .filter(([_, a]) => a)
    );

console.log(result);

Answer 4

Using the reduce method effectively ensure u run a single loop with a conditional inside, instead of a map and a filter like the previous answers which are both definitely correct as well

let data = [{q: "question 1",a: "answer 1"},{q: "question 2"}]

const obj = data.reduce((acc,cur) => {
If(cur.a && cur.q) {
acc.push({[`${cur.q}`]: cur.a})
}. 
return acc
} ,[])

console.log(obj)