Local and Global Variables in JavaScript

1. Global Variables

A global variable is declared outside of any function and can be accessed from anywhere in the code (inside or outside functions).

Example:

let globalVar = "I am global";

function showGlobal() {
  console.log(globalVar); // Can access globalVar
}

showGlobal();
console.log(globalVar); // Also accessible here

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2. Local Variables

A local variable is declared inside a function (or block using let/const) and can only be accessed within that function or block.

✅ Example:

function showLocal() {
  let localVar = "I am local";
  console.log(localVar); // OK
}

showLocal();
// console.log(localVar); // Error: localVar is not defined

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Block Scope with let and const

Variables declared with let or const are block-scoped, which means they're only accessible within { } braces.

if (true) {
  let blockVar = "Inside block";
  console.log(blockVar); // OK
}
// console.log(blockVar); //  Error

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Note on var

var is function-scoped but not block-scoped.

function testVar() {
  if (true) {
    var x = 10;
  }
  console.log(x); //  Works: x is function-scoped
}
testVar();

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Comparison Table

Type	Scope	Accessible From	Keyword
Global	Entire script	Anywhere	var, let, const (outside)
Local	Function/Block	Only inside its block	let, const, var (inside)

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Summary

• Global Variable = Accessible anywhere in the file.
• Local Variable = Accessible only inside the function or block where it’s declared.

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