How to remove key based on condition in array object javascript

Question

I would like to know how to remove particular key in object array javascript. In the array object obj, if the id is null remove the key in javascript

var obj = [{
  id: 1,
  field: "finance"
}, {
  id: null,
  field: "service}, {
  id: 2,
  field: "information"
}]

functionremoveKey(arrobj) {
  return arrobj.filter(e => {
    if (e.id == null) {
      delete e.id;
    }
  }
}

var result = removeKey(obj);

Expected Output:

{
  { id: 1, field: "finance" },
  { field: "service" },
  { id: 2, field: "information" }
]

That's not what .filter() is meant to be used for/as. You either want .forEach() or .map() — Andreas
– Andreas, Commented May 20, 2020 at 9:35
Try this obj.forEach(e => { if (e.id === null) { delete e.id } }); — Mridul
– Mridul, Commented May 20, 2020 at 9:46

Rajneesh · Accepted Answer · 2020-05-20 09:57:23Z

1

You can make use of map for this:

var obj = [{ id: 1, field: "finance"}, { id: null, field: "service"}, { id: 2, field: "information"}]
result = obj.map(val=>val.id ? val : (delete val.id, val));
console.log(result);

answered May 20, 2020 at 9:57

Rajneesh

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Comments

Andy Cox · Accepted Answer · 2020-05-20 09:47:30Z

As Andreas mentions you'll want to iterate over the elements and remove the key rather than trying to filter the whole array. Something like the following would work:

var arr = [
    { id: 1, field: "finance" },
    { id: null, field: "service" },
    { id: 2, field: "information" }
];

function removeKey(arr) {
    arr.forEach(element => {
        if (element.id == null) {
            delete element.id;
        }                
    });
}

removeKey(arr);
console.log(arr);

FZs · Accepted Answer · 2020-05-20 09:50:56Z

If you don't want to mutate the source, you can use the following:

var obj = [{
  id: 1,
  field: "finance"
}, {
  id: null,
  field: "service"
}, {
  id: 2,
  field: "information"
}]

function removeKey(arrobj, keyname) {
  return arrobj.map(e => 
    Object.fromEntries(
      Object.entries(e).filter(
        ([k, v]) => v !== null || keyname !== k
      )
    )
  )
}

console.log(removeKey(obj, 'id'));

It makes use of the Object.fromEntries method, which is relatively new, if your environment doesn't support it, use this instead:

var obj = [{
  id: 1,
  field: "finance"
}, {
  id: null,
  field: "service"
}, {
  id: 2,
  field: "information"
}]

function removeKey(arrobj, keyname) {
  return arrobj.map(e => 
    Object
      .entries(e)
      .filter(([k, v]) => v !== null || keyname !== k)
      .reduce((obj, [k, v]) => (obj[k] = v, obj), {})
  )
}

console.log(removeKey(obj, 'id'));

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