filter array with unique objects javascript

1const array =
2  [
3    { "name": "Joe", "age": 17 },
4    { "name": "Bob", "age": 17 },
5    { "name": "Carl", "age": 35 }
6  ]
7
8const key = 'age';
9
10const arrayUniqueByKey = [...new Map(array.map(item =>
11  [item[key], item])).values()];
12
13console.log(arrayUniqueByKey);
14
15   /*OUTPUT
16       [
17        { "name": "Bob", "age": 17 },
18        { "name": "Carl", "age": 35 }
19       ]
20   */
21
22 // Note: this will pick the last duplicated item in the list.

1//ES6
2let array = [
3  { "name": "Joe", "age": 17 },
4  { "name": "Bob", "age": 17 },
5  { "name": "Carl", "age": 35 }
6];
7array.map(item => item.age)
8  .filter((value, index, self) => self.indexOf(value) === index)
9
10> [17, 35]

1const unique = [...new Set(array.map(item => item.age))];