How to convert boolean object to array

Question

How can I take a simple object with boolean values and convert it to an array where only those keys whose values are true end up in the array?

E.g.:

myObject = {
  option1: true,
  option2: false,
  option3: true,
  option4: true
}

becomes

['option1','option3','option4']

I tried using _.pick(myObject, Boolean) as suggested here, but that simply produced an empty object. I'm using Typescript, so if there's any Typescript magic I can use to accomplish this, I'm up for that, too.

`Object.entries(myObject).filter(([_,v]) => v).map(([k]) => k)` — 000, Aug 25 '17 at 23:35

score 12 · Answer 1 · answered Aug 25 '17 at 23:36

12

This is easily achievable with vanilla js.

let myObject = {
  option1: true,
  option2: false,
  option3: true,
  option4: true
}

let array = Object.keys(myObject).filter(key => myObject[key]);

console.log(array);

You can see a working example here.

answered Aug 25 '17 at 23:36

toskv

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Good solution with pure javascript :) .. but why you mentioned `vanilla js`? – Koushik Chatterjee Aug 26 '17 at 19:03
ooh.. just a alias.. anyway, +1 ^^ – Koushik Chatterjee Aug 26 '17 at 21:11

score 7 · Answer 2 · answered Aug 25 '17 at 23:40

A lodash solution is to use lodash#pickBy and lodash#keys to get all truthy keys.

var result = _(myObject).pickBy().keys().value();

var myObject = {
  option1: true,
  option2: false,
  option3: true,
  option4: true
};

var result = _(myObject).pickBy().keys().value();

console.log(result);

.as-console-wrapper{min-height:100%;top:0;}

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.min.js"></script>

Koushik Chatterjee · Answer 3 · 2017-08-27T12:13:00.303

in map function of Lodash it also handle Object, instead of a collection. using lodash the simplest solution will be using _.reduce.

Ohk.. let's see how _.map works with object:

var array = _(myObject).map((v, k)=> v && k).compact().value();

var myObject = {
  option1: true,
  option2: false,
  option3: true,
  option4: true
}
var array = _(myObject).map((v, k)=> v && k).compact().value();

console.log(array)

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.js"></script>

With the same concept, (that lodash and underscore handle object if you pass in place of array) you can use _.reduce function and do the trick in one go:

var array = _.reduce(myObject, (i, v, k) => v && !i.push(k) || i, []);

var myObject = {
  option1: true,
  option2: false,
  option3: true,
  option4: true
}
var array = _.reduce(myObject, (i, v, k) => v && !i.push(k) || i, []);

console.log(array);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.js"></script>

How to convert boolean object to array

3 Answers3