Objects, Methods, Scope & Hoisting

Object Literals

Objects store key-value pairs in { }. Keys are strings (or symbols); values can be any type.

Real-life example: A student file — name, roll, class — all details on one card.

const user = {
  name: "Asha",
  age: 16,
  city: "Delhi",
};
console.log(user.name); // dot notation
console.log(user["city"]); // bracket notation

Properties and Methods

A property holds data. A method is a function inside an object.

Real-life example: A phone object — brand (property), call() (method you can use).

const calc = {
  brand: "Simple",
  add(a, b) {
    return a + b;
  },
};
console.log(calc.add(2, 3)); // 5

this (brief)

Inside a method, this refers to the object that owns the method.

Real-life example: When you say "my phone", "my" points to you — this points to the object calling the method.

const shop = {
  name: "Rishtaara",
  welcome() {
    return "Welcome to " + this.name;
  },
};
console.log(shop.welcome());

Scope — global, function, block

Scope is where a variable can be used. Global — whole program. Function — inside that function. Block — inside { } with let/const.

Real-life example: Global = school notice board (everyone sees). Function = one classroom diary. Block = one desk drawer.

const globalVar = "everywhere";

function demo() {
  const fnVar = "inside function";
  if (true) {
    const blockVar = "inside block";
    console.log(blockVar); // OK
  }
  // console.log(blockVar); // Error
}

Hoisting (brief)

var declarations and function declarations are moved to the top of their scope in memory — but only var is initialized as undefined until the line runs.

let and const are hoisted but not usable before the line — Temporal Dead Zone.

Real-life example: Hoisting is like reserving a seat name before the person sits — var seat exists empty early; let seat is locked until arrival.

console.log(x); // undefined (var hoisted)
var x = 5;

// console.log(y); // Error — let not initialized yet
let y = 10;