🌍 Scope in JavaScript

2 min readSep 23, 2025

👉 Scope means: “where can I access a variable in my code?”

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There are different kinds of scopes in JavaScript: Global, Function, Block, and Lexical.
Here, we’ll focus on Global Scope and Lexical Scope.

1️⃣ Global Scope

A variable declared outside of any function/block is in the global scope.
Accessible anywhere in the program.
In browsers → attached to the window object.

📌 Example:

let globalVar = "I am Global";

function showGlobal() {
  console.log(globalVar); // ✅ Accessible
}

showGlobal();
console.log(globalVar); // ✅ Accessiblefunction showGlobal() {
  console.log(globalVar); // ✅ Accessible
}

2️⃣ Lexical Scope

Lexical = “defined in source code (at writing time)”.
Inner functions can access variables from their parent scope, even if called elsewhere.
This rule enables closures.

📌 Example:

function outer() {
  let outerVar = "I am from Outer";

  function inner() {
    console.log(outerVar); // ✅ inner can access outerVar
  }  inner();
}outer();

function outer() {
  let outerVar = "I am from Outer";

  function inner() {
    console.log(outerVar); // ✅ inner can access outerVar
  }

  inner();
}

outer();

Here:

outerVar is not in inner()’s local scope.
But because of lexical scope, inner() can access it.

3️⃣ ⚡ Key Difference

Scope TypeDefined ByAccessible Where?Global ScopeDeclared outside functions/blocksEverywhere in programLexical ScopeDetermined at code writing time by nestingInner functions can access outer scope variables

✅ Real-Life Example

let globalName = "Hari"; // Global Scope

function greet() {
  let message = "Hello"; // Local to greet()

  function display() {
    // Lexical Scope: has access to parent function's variables
    console.log(message + " " + globalName);
  }

  display();
}

greet(); // "Hello Hari"

globalName → Global Scope