isolate key value pairs in array of objects that have null value

July 28, 2022

I’m trying to create a new object that contains all of the key/value pairs from an object where the values are null. Here is the code thus far –

    const d = { pp: 1700, no: 2300, co: null, ng: 4550, zx: null };
    const nulls = {};

    Object.entries(d).forEach(([k, v]) => v === null ? nulls[k]: v);
    console.log(nulls);

The desired outcome is that the nulls object contains { co: null, zx: null }; however, the code above causes nulls to be an empty object.

What needs to be modified to get the necessary output? Maybe there is a more concise approach…possibly using .filter()?

>Solution :

As you have mentioned filter is a possible approach and after that convert back to an object using Object.fromEntries

const d = { pp: 1700, no: 2300, co: null, ng: 4550, zx: null };


const res = Object.fromEntries(Object.entries(d).filter(([k,v]) => v===null))
console.log(res)

possible solution using reduce

 const d = { pp: 1700, no: 2300, co: null, ng: 4550, zx: null };


 const res = Object.entries(d).reduce((acc,[k,v])=> {
  if(v===null)acc[k]=v
  return acc
 },{})
 
 console.log(res)