How to remove undefined property from object?

Question

I have this object:

  this.prepaidObject = {
            'customerType' : this.prepaidDetailForm.prepaidDetails.customerType,
            'firstName' : this.prepaidDetailForm.prepaidDetails.firstName,
            'lastName' : this.prepaidDetailForm.prepaidDetails.lastName,
            'note' : this.prepaidDetailForm.prepaidDetails.note,
            'created': this.prepaidDetailForm.prepaidDetails.created
        };

Now sometimes some of this property are undefined. What i want is if one of this.prepaidDetailForm.prepaidDetails properties are undefined not to display them. So for example if this.prepaidDetailForm.prepaidDetails.firsName is undefined i dont need to create 'firstName' property isnide object. Any suggestion how can i do that?

`if (typeof X !== "undefined") this.prepaidObject["key"] = X;` — Alex K., May 24 '17 at 11:07
Why You want to delete added property if You can simply check and add only _"valid"_ properties? — Andrew D., May 24 '17 at 11:51

score 6 · Accepted Answer · answered May 24 '17 at 11:08

6

Check your object:

    for( var m in this.prepaidObject ) {
        if ( this.prepaidObject[m] == undefined ) {
            delete this.prepaidObject[m];
        }
    }

answered May 24 '17 at 11:08

SPlatten

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could we loop over objects ? – SeleM May 24 '17 at 11:22
Yes, in the loop I post m becomes the member reference. – SPlatten May 24 '17 at 11:23
Honestly , that's brand new to me , X'D, I thought you could do it using the forEach of ES6 (e.g), but in this way , I do not know it. – SeleM May 24 '17 at 11:24
3

this syntax has been around in Javascript for years, trust me it works. – SPlatten May 24 '17 at 11:25
PS: am not the one who asked, just coming through and saw it , here is a +1 :D – SeleM May 24 '17 at 11:26

score 5 · Answer 2 · answered Apr 18 '20 at 09:16

The shortest way to do this is to parse it after stringify.

The exact syntax:

let prepaidObjectNew = JSON.parse(JSON.stringify(prepaidObject))

Example

Before:

var prepaidObject = {
    'customerType' : 'TestCustType',
    'firstName' : "sample FirstName",
    'lastName' : "sample LastName",
    'note' : undefined
 };

After:

{
    'customerType' : 'TestCustType',
    'firstName' : "sample FirstName",
    'lastName' : "sample LastName"
 };

Ovidiu Dolha · Answer 3 · 2017-05-24T11:18:38.480

One way is to go through the keys and only append the defined ones:

this.prepaidObject = { };
Object.keys(this.prepaidDetailForm.prepaidDetails)
     .forEach(function(key) {
           var val = this.prepaidDetailForm.prepaidDetails[key];
           if (val !== undefined) {
                this.prepaidObject[key] = val;
           }
     });

This is assuming the keys in prepaidObject are the same as in prepaidDetails and all of them follow the same rule you mention.

Especially if you're using ES6 you might make this more elegant using map and reduce like so:

this.prepaidObject = Object.keys(this.prepaidDetailForm.prepaidDetails)
     .map(key => ({key, val: this.prepaidDetailForm.prepaidDetails[key]}))
     .reduce((obj, {key, val}) => {
          if (val !== undefined) {
               obj[key] = val;
          }
          return obj;
     }, {});

And an even more succinct approach using more ES6 features:

this.prepaidObject = Object.keys(this.prepaidDetailForm.prepaidDetails)
     .map(key => ({key, val: this.prepaidDetailForm.prepaidDetails[key]}))
     .filter(({_, val}) => val !== undefined)
     .reduce((obj, {key, val}) => Object.assign(obj, { [key]: val }), {});

score 1 · Answer 4 · answered May 24 '17 at 11:34

1

Using Lodash make it too easy in one line:

_.pickBy(this.prepaidObject, _.identity);

That would remove all falsey values

answered May 24 '17 at 11:34

SeleM

9,310
5
32
51

score 0 · Answer 5 · answered May 24 '17 at 11:07

0

You probably need to check the type.

(typeof(this.prepaidDetailForm.prepaidDetails.firsName) != "undefined") ? this.prepaidDetailForm.prepaidDetails.firsName : ''

Its basically:

var firstName = '';
if(typeof(this.prepaidDetailForm.prepaidDetails.firsName) != "undefined")
     firstName = this.prepaidDetailForm.prepaidDetails.firsName;

answered May 24 '17 at 11:07

Milan Chheda

8,159
3
20
35

that is a bit naughty , it should be kicked out automatically , not testing on a fixed key's value. ;) – SeleM May 24 '17 at 11:20

titech · Answer 6 · 2017-05-24T14:32:55.433

0

Please try following:

 for (var propName in this.prepaidObject) { 
    if (this.prepaidObject[propName] === undefined) {
      delete this.prepaidObject[propName];
    }
  }

And look at following answers: Remove blank attributes from an Object in Javascript

edited May 24 '17 at 14:32

answered May 24 '17 at 11:11

titech

197
4
13

score 0 · Answer 7 · answered May 24 '17 at 11:15

this.prepaidObject = {};
for (var i in this.prepaidDetailForm.prepaidDetails) {
  if (typeof(this.prepaidDetailForm.prepaidDetails[i]) !== 'undefined') {
    this.prepaidObject[i] = this.prepaidDetailForm.prepaidDetails[i];
  } 
}

If you want to exclude also null values and undefined, change the condition to:

if (this.prepaidDetailForm.prepaidDetails[i] != null)

Not the double ==. because null == undefined but null !== undefined

score 0 · Answer 8 · answered May 24 '17 at 11:23

Assume you have an object like below one,

var prepaidObject = {
    'customerType' : 'TestCustType',
    'firstName' : "sample FirstName",
    'lastName' : "sample LastName",
    'note' : undefined
 };

You can remove undefined using JSON.parse and JSON.stringify method,

JSON.parse(JSON.stringify(prepaidObject));
console.log(prepaidObject)

Output will be,

{
    'customerType' : 'TestCustType',
    'firstName' : "sample FirstName",
    'lastName' : "sample LastName"
 }

How to remove undefined property from object?

8 Answers8