check how many unique values are in array javascript code example

Example 1: javascript get unique values from key

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

Example 2: get only unique values from array javascript

arr = [2, 2, 2, 1, 3, 3, 3,3, 4, 5];
arr = arr.sort().filter((item,i)=>!(arr[i] == arr[i+1] || arr[i-1]==arr[i]));
// this will remove all item which are repeating more then one
console.log(arr);
// [1, 4, 5]