JavaScript Classes — Syntax, Inheritance, and Modern Features

hello@ghafoorsblog.com (AG Sayyed) — Thu, 31 Jul 2025 08:00:00 +0000

Classes are sugar — but very useful sugar

The class keyword arrived in ES2015 and has been steadily extended ever since. Under the hood it is still the prototype model from the previous post — but the syntax is cleaner, the semantics are stricter, and modern additions (private fields, static blocks) genuinely solve real problems.

Foundations: Objects — the basics, Prototypes and the chain.

A complete class at a glance

 1class Account {
 2 #balance; // private field, brand-checked
 3
 4 static minimumDeposit = 1; // static (class-level) field
 5
 6 constructor(owner, opening = 0) {
 7 this.owner = owner;
 8 this.#balance = opening;
 9 }
10
11 // Instance method — lives on Account.prototype
12 deposit(amount) {
13 if (amount < Account.minimumDeposit) throw new RangeError("too small");
14 this.#balance += amount;
15 return this;
16 }
17
18 // Getter — accessed without ()
19 get balance() {
20 return this.#balance;
21 }
22
23 // Static method — called on the class itself
24 static from(plain) {
25 return new Account(plain.owner, plain.balance);
26 }
27}
28
29const a = Account.from({ owner: "Ali", balance: 100 });
30a.deposit(20).deposit(5);
31a.balance; // 125

That single example uses every feature this post covers.

Oop on Ghafoor's Personal Blog

JavaScript Classes — Syntax, Inheritance, and Modern Features

Classes are sugar — but very useful sugar

A complete class at a glance