Summary

Today's topic will be about the Optional Chaining (?.) operator that appears in top Javascript interview questions. Optinal Chaining is used in many places and is considered one of the most necessary operators. Let's start with what it is!

Category

JavaScript

Optional Chaining

Javascript interview

Interview

JavaScript operator

Cover

Slug

javascripda-optional-chaining

Date

‣

author

Published

Published

let user = {
  name: 'Anvarbek',
  address: {
    city: 'Toshkent',
    street: 'Navoiy ko‘chasi'
  }
};

console.log(user.address.city); // Toshkent

let user = {
  name: 'Anvar'
};

console.log(user.address.city); // TypeError: Cannot read property 'city' of undefined

if (user.address && user.address.city) {
  console.log(user.address.city);
}

console.log(user.address?.city); // undefined (No error occurs)

1. When accessing object fields:

let user = {};
console.log(user.profile?.age); // undefined

1. When accessing array elements:

let users = null;
console.log(users?.[0]); // undefined

1. When calling functions:

let user = {
  sayHello: function() {
    return "Salom!";
  }
};

console.log(user.sayHello?.()); // Hello!
console.log(user.sayGoodbye?.()); // undefined, no error