How to return an object only with keys that have a number value?

Question

I have the following Object

{date_created: 1546293600000, num: 370, num2: NaN, num3: 100, category: "C"}

I would my output to be

{num: 370, num3: 100}

Removing date_created, num2, and category ideally it would remove also anything that is null or undefined in the value

But date_created is a number. That aside, see https://stackoverflow.com/questions/30726830/how-to-filter-keys-of-an-object-with-lodash — jarmod, Dec 18 '19 at 13:23
@jarmod that's fine if he's already using lodash for something else. But I wouldn't advise anyone to include a library for a such simple task — Christian Vincenzo Traina, Dec 18 '19 at 13:29
You want to remove `date_created`, `num2` and `category` irrespective of their value and in addition to those, any key with null or undefined value? It's not exactly clear — adiga, Dec 18 '19 at 13:33
@CristianTraìna agreed, you can solve this readily in native JavaScript these days. — jarmod, Dec 18 '19 at 13:37

kooskoos · Answer 1 · 2019-12-18T13:42:01.927

2

Object.keys(obj).filter(key => !isNaN(obj[key]))

let obj = {
  date_created: 1546293600000,
  num: 370,
  num2: NaN,
  num3: 100,
  category: "C"
}

let keys = Object.keys(obj).filter(key => !isNaN(obj[key]))
let newObj = {}
keys.forEach(key => newObj[key] = obj[key])
console.log(newObj)

edited Dec 18 '19 at 13:42

answered Dec 18 '19 at 13:24

kooskoos

4,622
1
12
29

score 2 · Answer 2 · edited Dec 18 '19 at 13:39

2

You can use filter to filter out all the NaN values (Not A Number, so also strings, objects, etc). Then re-map the keys to get the values:

const obj = {date_created: 1546293600000, num: 370, num2: NaN, num3: 100, category: "C"}

const newObj = Object.keys(obj)
  .filter(key => !isNaN(obj[key]))
  .reduce((acc, key) => {
    acc[key] = obj[key];
    return acc;
  }, {});

  
console.log(newObj);

In your example you filtered out date_created but what's your rationale?

edited Dec 18 '19 at 13:39

jarmod

71,565
16
115
122

answered Dec 18 '19 at 13:27

Christian Vincenzo Traina

9,546
2
40
63

You can loop only once by filtering within the reduce – Jeffrey Devloo Dec 18 '19 at 13:29
Personal opinion, but I find this format more readable. In this way you know exactly what you're filtering out, and you can easily chain a new `filter` or a `map`. Obviously it's not performance-oriented – Christian Vincenzo Traina Dec 18 '19 at 13:31
Sometimes beauty > performance. I agree that it is more readable :) – Jeffrey Devloo Dec 18 '19 at 13:33

ZektorH · Answer 3 · 2019-12-18T13:27:37.120

You can do this with the Object.keys property and a filter

var myObject = {
  date_created: 1546293600000,
  num: 370,
  num2: NaN,
  num3: 100,
  category: "C"
};

var newObject = Object.keys(myObject)
.filter(key => {
  return !isNaN(myObject[key]);
}).reduce((output, key) => {
  output[key] = obj[key];
  return output;
}, {});

In regards to the "date_created" property, you could add something like this:

Ignore all properties that have "date" in their names, even if their values are numbers.

var newObject = Object.keys(myObject)
.filter(key => {
  if (key.includes("date")) return false;
  return !isNaN(myObject[key]);
}).reduce((output, key) => {
  output[key] = obj[key];
  return output;
}, {});

You can also use `Object.values()` to check the values directly. Be aware NaN is also of type number — Reyno, Dec 18 '19 at 13:27

score 1 · Answer 4 · answered Dec 18 '19 at 13:28

You can use a reduce function

function getNumbersObj(obj) {
  return Object.keys(obj).reduce((newObj, key) => {
    const value = obj[key];
    if (typeof value === 'number') {
      newObj[key] = value
    }
    return newObj
  }, {})
}

Edit: for date_created which is a number, you'd could explicitly filter out the key

function getNumbersObj(obj) {
  return Object.keys(obj).reduce((newObj, key) => {
    const value = obj[key];
    if (typeof value === 'number' && key !== 'date_created') {
      newObj[key] = value
    }
    return newObj
  }, {})
}

score 1 · Answer 5 · edited Dec 18 '19 at 13:50

1

You can use loop through with filter and return only numbers

 const objects = {
    date_created: 1546293600000,
    num: 370,
    num2: NaN,
    num3: 100,
    category: 'C'
    }

    let newObj = Object.keys(objects).filter( key => 
    !isNaN(key)) 
    
    console.log(newObj)

edited Dec 18 '19 at 13:50

Ericgit

6,089
2
42
53

answered Dec 18 '19 at 13:30

Suraj Auwal

322
3
9

score 1 · Answer 6 · answered Dec 18 '19 at 13:37

Not the best solution from efficiency point of view but here is a solution:

const originalObj = {
  date_created: 1546293600000,
  num: 370,
  num2: NaN,
  num3: 100,
  category: "C"
}

const objWithUndefined ={
  date_created: 1546293600000,
  num: 370,
  num2: NaN,
  num3: undefined,
  category: "C"
}
const objWithNull ={
  date_created: 1546293600000,
  num: null,
  num2: NaN,
  num3: 100,
  category: "C"
}

function modifyObject(original) {
  let newObj = Object.assign({}, original);

  delete newObj.date_created;
  delete newObj.num2;
  delete newObj.category;
  
  for (var prop in newObj) {
    if (newObj[prop] == undefined || newObj[prop] == null) {
      delete newObj[prop]

    }
  }
  return newObj;
}

console.log("original: " + JSON.stringify(modifyObject(originalObj), null, 2));
console.log("objWithUndefined: " + JSON.stringify(modifyObject(objWithUndefined), null, 2));
console.log("objWithNull: " + JSON.stringify(modifyObject(objWithNull), null, 2));

How to return an object only with keys that have a number value?

6 Answers6