How to get distinct values from an array of objects in JavaScript?

Question

Assuming I have the following:

var array = 
    [
        {\"name\":\"Joe\", \"age\":17}, 
        {\"name\":\"Bob\", \"age\":17}, 
        {\"name\":\"Carl\         


        

Answer 1

I know my code is little length and little time complexity but it's understandable so I tried this way.

I'm trying to develop prototype based function here and code also change.

Here,Distinct is my own prototype function.

<script>
  var array = [{
      "name": "Joe",
      "age": 17
    },
    {
      "name": "Bob",
      "age": 17
    },
    {
      "name": "Carl",
      "age": 35
    }
  ]

  Array.prototype.Distinct = () => {
    var output = [];
    for (let i = 0; i < array.length; i++) {
      let flag = true;
      for (let j = 0; j < output.length; j++) {
        if (array[i].age == output[j]) {
          flag = false;
          break;
        }
      }
      if (flag)
        output.push(array[i].age);
    }
    return output;
  }
  //Distinct is my own function
  console.log(array.Distinct());
</script>

Answer 2

const x = [
  {"id":"93","name":"CVAM_NGP_KW"},
  {"id":"94","name":"CVAM_NGP_PB"},
  {"id":"93","name":"CVAM_NGP_KW"},
  {"id":"94","name":"CVAM_NGP_PB"}
].reduce(
  (accumulator, current) => accumulator.some(x => x.id === current.id)? accumulator: [...accumulator, current ], []
)

console.log(x)

/* output 
[ 
  { id: '93', name: 'CVAM_NGP_KW' },
  { id: '94', name: 'CVAM_NGP_PB' } 
]
*/

Answer 3

If you have Array.prototype.includes or are willing to polyfill it, this works:

var ages = []; array.forEach(function(x) { if (!ages.includes(x.age)) ages.push(x.age); });

Answer 4

using lodash

var array = [
    { "name": "Joe", "age": 17 },
    { "name": "Bob", "age": 17 },
    { "name": "Carl", "age": 35 }
];
_.chain(array).pluck('age').unique().value();
> [17, 35]

Answer 5

i think you are looking for groupBy function (using Lodash)

_personsList = [{"name":"Joe", "age":17}, 
                {"name":"Bob", "age":17}, 
                {"name":"Carl", "age": 35}];
_uniqAgeList = _.groupBy(_personsList,"age");
_uniqAges = Object.keys(_uniqAgeList);

produces result:

17,35

jsFiddle demo:http://jsfiddle.net/4J2SX/201/

Answer 6

This is how you would solve this using new Set via ES6 for Typescript as of August 25th, 2017

Array.from(new Set(yourArray.map((item: any) => item.id)))