JavaScript Getters and Setters: Controlled Access to Object Properties

const user = {
  firstName: "Priya", lastName: "Sharma", // 📖 GETTER — runs when you READ fullName:  get fullName() {    return `${this.firstName} ${this.lastName}`;  }};
  // Looks like a property… no parentheses!console.log(user.fullName);    // "Priya Sharma" — the function ran! ✨

const user = {
  firstName: "Priya", lastName: "Sharma", // 📖 Called on READ:  get fullName() {    return `${this.firstName} ${this.lastName}`;  },
  // ✏️ Called on WRITE — receives the assigned value:  set fullName(value) {    const parts = value.split(" ");    this.firstName = parts[0];    this.lastName = parts[1];  }};
  // Reading → the GETTER runs:console.log(user.fullName);     // "Priya Sharma"
  // Writing → the SETTER runs:user.fullName = "Amit Verma";   // setter splits and stores!
  console.log(user.firstName);
  // "Amit" — updated automatically ✅console.log(user.lastName);     // "Verma" ✅console.log(user.fullName);     // "Amit Verma" — getter reflects changes

class BankAccount {
  #balance = 0;
  // 🔒 private field (Lesson 23!)
  constructor(owner, balance) {
    this.owner = owner;
    this.balance = balance;
    // goes THROUGH the setter — validated!  }
    // 📖 Read access:  get balance() {    return this.#balance;  }
    // ✏️ Write access — WITH A GUARD:  set balance(amount) {    if (typeof amount !== "number" || isNaN(amount)) {      console.log("❌ Balance must be a number!");      return;                        // rejected — door stays shut    }    if (amount < 0) {      console.log("❌ Balance can't be negative!");      return;    }    this.#balance = amount;          // ✅ passed inspection  }}
    const account = new BankAccount("Priya", 1000);
    console.log(account.balance);
    // 1000 ✅
    account.balance = 500;
    // ✅ valid — acceptedconsole.log(account.balance);      // 500
    account.balance = -99999;
    // ❌ "Balance can't be negative!"account.balance = "hello";         // ❌ "Balance must be a number!"console.log(account.balance);      // still 500 — protected! 🛡️
    console.log(account.#balance);
    // ❌ SyntaxError — truly private!

// 💀 BROKEN — infinite recursion:class BadAccount {
set balance(amount) {
  this.balance = amount;
  // 😱 this CALLS the setter again → again → again…
}// 💥 RangeError: Maximum call stack size exceeded
}

set balance(amount) {
  this.#balance = amount;
  // ✅ different name — no recursion
}// (older style you may see: this._balance = amount; — same idea, convention only)

class Rectangle {
  constructor(width, height) {
    this.width = width;
    this.height = height;
  } // Area is always correct — calculated fresh every read:  get area() {    return this.width * this.height;  }}
  const box = new Rectangle(10, 5);
  console.log(box.area);
  // 50
  box.width = 20;
  // change the input…console.log(box.area);     // 100 — area updated automatically! ✨

class Temperature {
  #celsius = 0;
  get celsius() {
    return this.#celsius;
  } set celsius(value) {
    this.#celsius = value;
  } get fahrenheit() {
    return (this.#celsius * 9 / 5) + 32;
    // compute on read  }
    set fahrenheit(value) {
      this.#celsius =(value - 32) * 5 / 9;
      // convert on write!  }}
      const temp = new Temperature();
      temp.celsius = 25;
      console.log(temp.fahrenheit);
      // 77 — translated automatically! ✅
      temp.fahrenheit = 212;
      console.log(temp.celsius);
      // 100 — reverse translation! ✅

// 🏠 Plain object literal:const product = {  _price: 499,                          // _ = "private by convention"
get price() {
  return `₹${this._price}`;
}, set price(value) {
  if (value > 0) this._price = value;
}
};
// 🏭 Class (from Lesson 23):class Product {  #price = 0;                           // # = truly private
get price() {
  return `₹${this.#price}`;
} set price(value) {
  if (value > 0) this.#price = value;
}
}

class Circle {
  constructor(radius) {
    this.radius = radius;
  } get area() {
    return (Math.PI * this.radius ** 2).toFixed(2);
  } // no setter — nobody can assign circle.area!}
  const c = new Circle(7);
  console.log(c.area);
  // "153.94" ✅c.area = 999;            // silently ignored (or TypeError in strict mode)console.log(c.area);     // still "153.94" — protected! 🛡️

// Style A — getter:get fullName() { return `${this.firstName} ${this.lastName}`; }user.fullName;                       // reads like data
// Style B — method:getFullName() { return `${this.firstName} ${this.lastName}`; }user.getFullName();                  // reads like an action

// 👤 User Profile — validation + computed properties + privacy
class UserProfile {
  #email = "";
  #age = 0;
  constructor(firstName, lastName) {
    this.firstName = firstName;
    this.lastName = lastName;
  } // 📖 Computed: always in sync
  get fullName() {
    return `${this.firstName} ${this.lastName}`;
  } // ✏️ Validated email (regex from Lesson 28! 🔍):
  get email() {
    return this.#email;
  } set email(value) {
    const emailPattern = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
    if (!emailPattern.test(value)) {
      console.log("❌ Invalid email address!");
      return;
    } this.#email = value.toLowerCase();
    // normalized on the way in ✨
  } // ✏️ Validated age with guard rails:
  get age() {
    return this.#age;
  } set age(value) {
    if (!Number.isInteger(value) || value < 0 || value > 120) {
      console.log("❌ Age must be a whole number between 0 and 120!");
      return;
    } this.#age = value;
  } // 📖 Computed from age:
  get canVote() {
    return this.#age >= 18;
  }
}// Test drive:
const user = new UserProfile("Priya", "Sharma");
user.email = "PRIYA@Example.COM";
console.log(user.email);
// "priya@example.com" — normalized! ✅
user.email = "not-an-email";
// ❌ Invalid email address!
user.age = 22;
console.log(user.canVote);
// true ✅
user.age = -5;
// ❌ Age must be a whole number…
user.age = "twenty";
// ❌ rejected too
console.log(user.fullName);
// "Priya Sharma"

priya@example.com❌ Invalid email address!true❌ Age must be a whole number between 0 and 120!❌ Age must be a whole number between 0 and 120!Priya Sharma