JavaScript Tutorial Classes and Object-Oriented JavaScript

JavaScript static Methods and Properties

Lesson 192 of 258 2 min read By Deepak Paswan Updated Oct 4, 2026

Normally, methods belong to instances: you call user.greet(). A static member belongs to the class itself: you call User.something(), and instances do not have it.

script.js

class MathUtil {
  static square(n) {
    return n * n;
  }
  static PI = 3.14159;
}

console.log(MathUtil.square(5)); // → 25
console.log(MathUtil.PI);        // → 3.14159

There is no need to create an instance. static is for things related to the class as a whole.

Factory methods

A static method that creates instances in a convenient way:

script.js

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

  static admin(name) {
    return new User(name, "admin");
  }

  static fromJSON(text) {
    const { name, role } = JSON.parse(text);
    return new User(name, role);
  }
}

console.log(User.admin("Maya").role);                         // → admin
console.log(User.fromJSON('{"name":"Sam","role":"editor"}').name); // → Sam

Shared counters and settings

script.js

class Widget {
  static count = 0;

  constructor() {
    Widget.count++;
  }
}

new Widget();
new Widget();
console.log(Widget.count); // → 2

Static vs instance

script.js

class Example {
  static hello() { return "static"; }
  hello() { return "instance"; }
}

console.log(Example.hello());        // → static
console.log(new Example().hello());  // → instance

An instance cannot call a static method directly (new Example().staticMethod is undefined). Inside a static method, this is the class.

Static blocks

A static initialization block runs once when the class is defined, for more complex setup.

script.js

class Config {
  static defaults;

  static {
    Config.defaults = { theme: "light", fontSize: 16 };
  }
}

console.log(Config.defaults.theme); // → light

Inheritance

Static members are inherited by subclasses.

script.js

class Animal {
  static kingdom = "Animalia";
}
class Dog extends Animal {}

console.log(Dog.kingdom); // → Animalia

Static private

static #cache = new Map(); and static #helper() {} also exist.

When to use static

Utility functions related to the class (Date.now(), Array.isArray(), Object.keys() are static methods you already use).
Factory methods and constructors with different inputs.
Class-level constants and counters.

If a static method does not relate to the class at all, a plain function in a module is clearer.