js filter unique 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 distinct values from array

const categories = ['General', 'Exotic', 'Extreme', 'Extreme', 'General' ,'Water', 'Extreme']
.filter((value, index, categoryArray) => categoryArray.indexOf(value) === index);

This will return an array that has the unique category names
['General', 'Exotic', 'Extreme', 'Water']