Ways to declare an object

JavaScriptJunior~1 min read

JavaScript has several ways to create an object, and the choice depends on what you need: a plain object, a copy, a template, or a class instance.

Here are all the main options:

1. Object literal - the simplest and most common way

javascript

const user = {
  name: 'Tim',
  age: 25
};

Creates a new object right away with the needed properties. This is the most common way in real code.

2. Via the `Object` constructor

javascript

const user = new Object();
user.name = 'Tim';
user.age = 25;

Works, but is usually not recommended, since literals ({}) are shorter and clearer.

3. Via `Object.create(proto)`

javascript

const person = { species: 'human' };
const user = Object.create(person);

user.name = 'Tim';
console.log(user.species); // "human" (inherited from person)

Lets you create an object with a specific prototype - often used in advanced scenarios (for example, when working with prototypes manually).

4. Via a constructor function

javascript

function User(name, age) {
  this.name = name;
  this.age = age;
}

const tim = new User('Tim', 25);
console.log(tim.name); // "Tim"

Constructor functions (with new) create objects of a specific "type" and automatically set this to the new object.

5. Via a class (`class`)

javascript

class User {
  constructor(name, age) {
    this.name = name;
    this.age = age;
  }
}

const tim = new User('Tim', 25);
console.log(tim.name); // "Tim"

Syntactic sugar over a constructor function, used in modern JS to create instances.

6. Via destructuring and spread

javascript

const base = { role: 'user' };
const user = { ...base, name: 'Tim', age: 25 };

Creates a copy of an existing object with new properties added.

7. Via `Object.fromEntries()`

javascript

const entries = [['name', 'Tim'], ['age', 25]];
const user = Object.fromEntries(entries);

console.log(user); // { name: 'Tim', age: 25 }

Useful when you need to create an object from key-value pairs (for example, after Object.entries() or Map).

Summary

Way	Example	When to use
Literal `{}`	`{ name: 'Tim' }`	the most common way
`new Object()`	`new Object()`	rarely, for compatibility
`Object.create(proto)`	`Object.create(person)`	needs prototype control
Constructor function	`new User()`	an old but working approach
`class`	`new User()`	a modern, OOP approach
Spread / copy	`{ ...obj }`	duplicating and extending objects
`Object.fromEntries()`	`Object.fromEntries(pairs)`	creating from key-value pairs

In one phrase:

In JS, an object can be created in many ways - from a plain {} to class, but in 95% of cases a literal {} or class is enough for structured data.

Short Answer

Interview ready

Premium

A concise answer to help you respond confidently on this topic during an interview.