return object property using lodash from array

Question

I have been trying to return a property of an object by filtering it first. Here's what I did:

var characters = [
  { 'name': 'barney',  'age': 36, 'blocked': false },
  { 'name': 'fred',    'age': 40, 'blocked': true },
  { 'name': 'pebbles', 'age': 1,  'blocked': false }
];

_.find(characters, function(chr) {
     return  chr.age == 40
});

It returns whole object where as I want to return specific property. Can anyone guide me how can I do it?

Any help will be appreciated.

Just access the property `age` after you filtered the object you need. — elclanrs, Aug 26 '14 at 18:44

aymericbeaumet · Accepted Answer · 2017-05-26T15:24:59.640

53

You could use the Lodash chaining ability. As its name implies, it enables you to chain Lodash methods calls. _.filter and _.map are appropriate here:

const characters = [
  { 'name': 'barney',  'age': 36, 'blocked': false },
  { 'name': 'fred',    'age': 40, 'blocked': true  },
  { 'name': 'pebbles', 'age': 1,  'blocked': false },
]

const names = _(characters)
  .filter(c => c.age < 40)
  .map('name')
  .value()

alert(names)

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.3.0/lodash.min.js"></script>

For the record, this is how you can do in pure JS:

const characters = [
  { 'name': 'barney',  'age': 36, 'blocked': false },
  { 'name': 'fred',    'age': 40, 'blocked': true  },
  { 'name': 'pebbles', 'age': 1,  'blocked': false },
]

const names = characters
  .filter(c => c.age < 40)
  .map(c => c.name)

alert(names)

edited May 26 '17 at 15:24

answered Aug 27 '14 at 14:42

aymericbeaumet

6,853
2
37
50

it works, i have used find over filter is because filter loop through all values and then return matched array. thanks for helping me out – Salman Aug 30 '14 at 11:02
4

`pluck` isn't in lodash anymore :( – SSH This Feb 09 '16 at 16:24
1

I updated the answer to match this API update, actually `pluck` is simply a `map`. This is actually even clearer with the ES6 arrow functions. – aymericbeaumet Feb 10 '16 at 14:06
`_.map` also supports the `_.property` iteratee shorthand like `_.map(characters, 'name')` – Brandon Copeland Mar 16 '16 at 14:16

Chun Yang · Answer 2 · 2016-10-25T01:48:25.760

7

_.property

var array = [{a: 1, b: 2}, {a: 3, b: 4}]
array.map(_.property('a')) // => [1, 3]

_.map short hand

var array = [{a: 1, b: 2}, {a: 3, b: 4}]
_.map(array, 'a') // => [1, 3]

edited Oct 25 '16 at 01:48

answered Aug 26 '15 at 16:00

Chun Yang

2,451
23
16

score 7 · Answer 3 · answered Oct 13 '15 at 17:06

7

_.result(_.find(characters, function(obj) {
       return obj.age === 40;
}), 'name');

answered Oct 13 '15 at 17:06

Ninja

2,050
1
23
27

score 0 · Answer 4 · answered Aug 27 '14 at 14:36

0

As elclanrs mentioned in comment before obvious solution is just to access the property age after you filtered the object.

But if you wanted to be done in method, you can first extract all age values and then allpy find function on them:

var ageValues = _.pluck(characters, 'age'); //returns [36, 40, 1]

var resultAgeValue = _.find(ageValues, function(ageValue) {
   return  ageValue < 40
});

or, better looks in chain:

var resultAgeValue = _(characters).pluck('age').find(function(ageValue) {
   return  ageValue < 40
});

try jsFiddle: http://jsfiddle.net/pqr/j8rL780u/

answered Aug 27 '14 at 14:36

Petr

7,275
2
16
16

Your fiddle doesn't work, it only returns the first matching character. – aymericbeaumet Aug 27 '14 at 14:57
Actually my jsfiddle returns the first matching character by desing! The original code in the question also returns only first matching object - author was using `find`, not `filter`! – Petr Aug 27 '14 at 15:07
The author appears to begin with Lodash. It doesn't make much sense to return only one value when considering a non-sorted array. Hence my use of `filter`. – aymericbeaumet Aug 27 '14 at 15:12

return object property using lodash from array

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