how many unique in array javascript code example

Example 1: 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 2: javascript array unique values

var arr = [55, 44, 65,1,2,3,3,34,5];
var unique = [...new Set(arr)]

//just  var unique = new Set(arr) wont be an array