JavaScript - get unique objects from array

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

The main idea to find unique objects is to create text representation for each object and check them if are unique.

Practical example:

// ONLINE-RUNNER:browser;

const getUniqueItems = (items, keyGetter) => {
    const locks = {};
    const result = [];
    for (const item of items) {
        const key = keyGetter(item);
        if (key in locks) {
            continue;
        }
        locks[key] = true;
        result.push(item);
    }
    return result;
};


// Usage example:

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

const keyGetter = (item) => item.name + ' ' + item.age;  // change it to your own criteria
const uniqueItems = getUniqueItems(items, keyGetter);

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

Note: it is important to create correct valueGetter function or use universal one, e.g. JSON.stringify() improved with ordered properties.

See also

1. TypeScript - get unique objects from array

2. JavaScript - convert object to JSON with ordered properties