Javascript how to set null/undefined values in an Object to an empty string

Question

I have an object where some fields have a value of null or undefined. Is there a nice quick way to change these values to an empty string '' using Javascript or Lodash?

Example input:

{
  a: '23',
  b: 'Red',
  c: null,
}

Example output:

{
  a: '23',
  b: 'Red',
  c: '',
}

NOTE: I do NOT want to remove these fields with values of null or undefined, I want to keep them in the object but change their values to the empty string ''

Thanks

Ori Drori · Accepted Answer · 2019-05-10 13:58:52Z

3

You can use _.mapValues() to iterate the values and replace them, and _.isNil() to check if a value is null or undefined:

const obj = {
  a: '23',
  b: 'Red',
  c: null,
}

const result = _.mapValues(obj, v => _.isNil(v) ? '' : v)

console.log(result)

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.js"></script>

answered May 10, 2019 at 13:58

Ori Drori

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1 Comment

tnoel999888 Over a year ago

This is very nice thank you! Accepting this answer instead as it is shorter and easier to read

Pointy · Accepted Answer · 2019-05-10 13:36:46Z

3

You can use a combination of Object.keys() and .forEach():

Object.keys(yourObject).forEach(function(key, index) {
  if (this[key] == null) this[key] = "";
}, yourObject);

The == comparison will check for both null and undefined. Passing yourObject as the second parameter to .forEach() will cause this to be bound to it inside the callback function.

edit — originally I wrote this as an => function, but that won't work because we need this to work in the traditional way.

edited May 10, 2019 at 13:36

answered May 10, 2019 at 13:21

Pointy

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6 Comments

Pointy Over a year ago

@tnoel999888 without seeing your actual code it's going to be hard to help. You can edit it into your question.

tnoel999888 Over a year ago

ah fair enough, edited the post to include my actual code

Pointy Over a year ago

@tnoel999888 oh oh sorry, my bad; it'll need an old-style function. I'll update the answer.

Pointy Over a year ago

@tnoel999888 sorry I don't use => functions in my own code due to various particular constraints I'm under, so I'm not really used to thinking about how they work etc :)

tnoel999888 Over a year ago

Thanks working now! Accepted answer. Also would it be possible instead of having both arguments (key, index) i could just have one say field and then it becomes if (field == null) field = "";?

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