? JavaScript Scope

Scope defines the accessibility or lifetime of variables and functions in your code. It determines where a variable can be accessed.

Types of Scope in JavaScript

1. Global Scope

• Variables declared outside any function or block.

• Accessible from anywhere in the code.

var globalVar = "I'm global";function test() {  console.log(globalVar);  // Accessible here}test();console.log(globalVar);    // Accessible here too

2. Function Scope

• Variables declared inside a function using var are scoped to that function.

• Not accessible outside the function.

function example() {  var localVar = "I'm local";  console.log(localVar);  // Works here}example();console.log(localVar);    // Error: localVar is not defined

3. Block Scope (ES6+)

• Variables declared with let or const inside {} blocks (like inside if, for) are scoped to that block.

if (true) {  let blockVar = "I'm block scoped";  const blockConst = 42;  console.log(blockVar);    // Accessible here}console.log(blockVar);      // Error: blockVar is not definedconsole.log(blockConst);    // Error: blockConst is not defined

Scope Chain

• When accessing a variable, JavaScript looks in the current scope.

• If not found, it looks in the outer scope, continuing up to the global scope.

• If variable is not found anywhere, it's undefined or throws ReferenceError if accessed before declaration (for let/const).

Example of Scope Chain

let a = "global";function outer() {  let b = "outer";  function inner() {    let c = "inner";    console.log(a); // global    console.log(b); // outer    console.log(c); // inner  }  inner();}outer();

Summary

If you want, I can also explain hoisting and how it relates to scope!