JavaScript - how to get unique objects

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Dirask Community

In this article, we would like to show you how in JavaScript find unique objects in the array.

Below example presents how to create a function that returns unique objects using:

  • locks object to store unique object as JSON,
  • valueGetter that creates normalized JSON objects located in the array.


As normalized JSON we understand JSON with ordered properties - below example, we take care of properties order.

Practical example:

// ONLINE-RUNNER:browser;

const getUniqueItems = (items, valueGetter) => {
const locks = {};
  const result = [];
  for (const item of items) {
      const value = valueGetter(item);
    if (value in locks) {
       locks[value] = true;
  return result;

// Usage example:

const items = [
 {name: 'john',  age: 20},
 {name: 'anna',  age: 25},
 {age: 20, name: 'john'},

const valueGetter = (item) => JSON.stringify({name:, age: item.age});
const uniqueItems = getUniqueItems(items, valueGetter);

console.log(JSON.stringify(uniqueItems, null, 4));


We must remember to create the valueGetter function ourselves or provide a generic function.

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