javascript find number of unique values in array 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: javascript get unique values from array

const myArray = [1,2,3,1,5,8,1,2,9,4];
const unique = [...new Set(myArray)]; // [1, 2, 3, 5, 8, 9, 4]

const myString = ["a","b","c","a","d","b"];
const uniqueString = [...new Set(myString)]; //["a", "b", "c", "d"]