[Edit]

JavaScript - check if object exists in array and add it if not

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Created by:

Savannah

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In this article, we would like to show you how to check if object exists in array and add it if not in JavaScript.

Practical example

Edit

In this example, we create a reusable arrow function that takes two arguments:

array to which we want to add an object,
name - the new object's (user) name property.

The function uses some() method to check if an object with a given name already exists and adds it if not.

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const addIfNotExists = (array, name) => {
    const id = array.length + 1;
    const found = array.some((item) => item.username === name);
    if (!found) array.push({ id, username: name });
    return array;
};
​
const users = [
    { id: 1, username: 'Tom' },
    { id: 2, username: 'Ann' },
];
​
addIfNotExists(users, 'Ann'); // username already exists, object won't be added
addIfNotExists(users, 'Kate');
​
console.log(JSON.stringify(users, null, 4)); // [ { id: 1, username: 'Tom' }, { id: 2, username: 'Ann' }, { id: 3, username: 'Kate' } ]