map unique values javascript code example

Example 1: filter array with unique objects javascript

const array =
  [
    { "name": "Joe", "age": 17 },
    { "name": "Bob", "age": 17 },
    { "name": "Carl", "age": 35 }
  ]

const key = 'age';

const arrayUniqueByKey = [...new Map(array.map(item =>
  [item[key], item])).values()];

console.log(arrayUniqueByKey);

   /*OUTPUT
       [
        { "name": "Bob", "age": 17 },
        { "name": "Carl", "age": 35 }
       ]
   */

 // Note: this will pick the last duplicated item in the list.

Example 2: unique array javascript es6 Map

const data = [
  { group: 'A', name: 'SD' }, 
  { group: 'B', name: 'FI' }, 
  { group: 'A', name: 'MM' },
  { group: 'B', name: 'CO'}
];
const unique = [...new Set(data.map(item => item.group))]; // [ 'A', 'B']

Example 3: javascript find unique values in array

// usage example:
var myArray = ['a', 1, 'a', 2, '1'];
var unique = myArray.filter((v, i, a) => a.indexOf(v) === i); 

// unique is ['a', 1, 2, '1']

Example 4: array unique values javascript

const myArray = ['a', 1, 'a', 2, '1'];
const unique = [...new Set(myArray)]; // ['a', 1, 2, '1']

Example 5: javascript unique array of objects by property

const array =
  [
    { "name": "Joe", "age": 17 },
    { "name": "Bob", "age": 17 },
    { "name": "Carl", "age": 35 }
  ]

function uniqueByKey(array, key) {
  return [...new Map(array.map((x) => [x[key], x])).values()];
}

console.log(uniqueByKey(array, 'age'));

Example 6: array with unique values javascript

let uniqueItems = [...new Set(items)]