lodash unique based on attribute

Question

I have a array of objects such as

[{ "name": "Jen", "age":31, "eyecolor": "blue", "hair":"brown"}, 
 { "name": "Jen", "age":32, "eyecolor": "green", "hair":"blonde"}, 
 { "name": "Jules", "age":31, "eyecolor": "blue", "hair":"brown"}, ,
 { "name": "Brian", "age":40, "eyecolor": "blue", "hair":"brown"}]

I need a lodash expression that will result in a array of unique objects based on one property. For example, if I used name, it would give me these three:

[{ "name": "Jen", "age":31, "eyecolor": "blue", "hair":"brown"}, 
 { "name": "Jules", "age":31, "eyecolor": "blue", "hair":"brown"}, 
 { "name": "Brian", "age":40, "eyecolor": "blue", "hair":"brown"}]

Answer 1

For Lodash versions 4+ use _.uniqBy():

var arr = [{"name":"Jen","age":31,"eyecolor":"blue","hair":"brown"},{"name":"Jen","age":32,"eyecolor":"green","hair":"blonde"},{"name":"Jules","age":31,"eyecolor":"blue","hair":"brown"},{"name":"Brian","age":40,"eyecolor":"blue","hair":"brown"}];

var unique = _.uniqBy(arr, 'name');

console.log(unique);

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

For Lodash versions under 4 use _.uniq():

var arr = [{"name":"Jen","age":31,"eyecolor":"blue","hair":"brown"},{"name":"Jen","age":32,"eyecolor":"green","hair":"blonde"},{"name":"Jules","age":31,"eyecolor":"blue","hair":"brown"},{"name":"Brian","age":40,"eyecolor":"blue","hair":"brown"}];

var unique = _.uniq(arr, 'name');

console.log(unique);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/3.10.1/lodash.js"></script>

Answer 2

If your lodash version is higher than 4.0, You should use _.uniqBy().

At this time, _.uniq() does not work, it only accept one parameter, which cannot address iterated objects.

var arr = [{ "name": "Jen", "age":31, "eyecolor": "blue", "hair":"brown"}, 
 { "name": "Jen", "age":32, "eyecolor": "green", "hair":"blonde"}, 
 { "name": "Jules", "age":31, "eyecolor": "blue", "hair":"brown"},
 { "name": "Brian", "age":40, "eyecolor": "blue", "hair":"brown"}];

var result = _.uniqBy(arr, 'name');
console.log(result)

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

Reference
https://lodash.com/docs/4.17.4#uniqBy