//ES6 let array = [ { "name": "Joe", "age": 17 }, { "name": "Bob", "age": 17 }, { "name": "Carl", "age": 35 } ]; array.map(item => item.age) .filter((value, index, self) => self.indexOf(value) === index) > [17, 35]
const unique = [...new Set(array.map(item => item.age))];
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'));