JavaScriptEasy

Explain the concept of scope in JavaScript

By FrontendPro Editorial Team Updated 8/8/2026

#JavaScript

Answer

In JavaScript, scope determines the accessibility of variables and functions at different parts of the code. There are three main types of scope: global scope, function scope, and block scope. Global scope means the variable is accessible everywhere in the code. Function scope means the variable is accessible only within the function it is declared. Block scope, introduced with ES6, means the variable is accessible only within the block (e.g., within curly braces {}) it is declared.

var globalVar = "I am a global var";

function myFunction() {
  var functionVar = "I am a function-scoped var";

  if (true) {
    let blockVar = "I am a block-scoped var";

    console.log("Inside block:");
    console.log(globalVar); // Accessible
    console.log(functionVar); // Accessible
    console.log(blockVar); // Accessible
  }

  console.log("Inside function:");
  console.log(globalVar); // Accessible
  console.log(functionVar); // Accessible
  // console.log(blockVar); // Uncaught ReferenceError
}

myFunction();

console.log("In global scope:");
console.log(globalVar); // Accessible
// console.log(functionVar); // Uncaught ReferenceError
// console.log(blockVar); // Uncaught ReferenceError