how to get unique object from array in javascript 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 find unique values in array

// usage example:
var myArray = ['a', 1, 'a', 2, '1'];
var unique = myArray.filter((v, i, a) => a.indexOf(v) === i); 

// unique is ['a', 1, 2, '1']

Example 3: javascript unique array of objects by property

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'));

Example 4: javascript remove duplicates from array

function toUniqueArray(a){
    var newArr = [];
    for (var i = 0; i < a.length; i++) {
        if (newArr.indexOf(a[i]) === -1) {
            newArr.push(a[i]);
        }
    }
  return newArr;
}
var colors = ["red","red","green","green","green"];
var colorsUnique=toUniqueArray(colors); // ["red","green"]