JavaScript Scope

Level : Intermediate

Mentor: Shailendra Chauhan

Duration : 00:01:00

Scope:

Scope in JavaScript defines the accessibility of variables and functions within different parts of the code. It determines where a variable or function can be accessed or modified.

Global Scope:

Variables declared outside of any functions or blocks have a global scope, making them accessible from anywhere in the code.

Example:

const globalVar = "I am global";
function exampleFunction() {
  console.log(globalVar); // Accessible here
}
console.log(globalVar); // Accessible here too

File or Module Scope:

In modular JavaScript, variables declared at the top level of a file (module) have a scope limited to that file, making them accessible only within that file.

Example:

// module.js
const moduleVar = "I belong to this module";
// main.js
console.log(moduleVar); // Will result in an error, moduleVar is not defined here

Function Scope:

Variables declared inside a function are limited to that function's scope, making them accessible only within the function.

Example:

function exampleFunction() {
  const functionVar = "I'm scoped within this function";
  console.log(functionVar); // Accessible here
}
console.log(functionVar); // Will result in an error, functionVar is not defined here

Code Block Scope:

JavaScript introduced block-scoped variables with 'let' and 'const', which are limited to the scope of a code block.

Example:

if (true) {
  let blockVar = "I'm scoped within this block";
  console.log(blockVar); // Accessible here
}
console.log(blockVar); // Will result in an error, blockVar is not defined here

Block Scoped Variables:

Using 'let' and 'const', variables can be declared with block scope, making them accessible only within the block they're defined in.

Example:

{
  let blockScopedVar = "I'm scoped within this block";
  console.log(blockScopedVar); // Accessible here
}
console.log(blockScopedVar); // Will result in an error, blockScopedVar is not defined here

Global Variables:

Variables declared outside of blocks or functions have global scope, which means they're accessible throughout the program.

Example:

const globalVar = "I'm accessible everywhere";
function exampleFunction() {
  console.log(globalVar); // Accessible here
}
console.log(globalVar); // Accessible here too

Self-paced Membership

Upto 60% OFF

Know More

Still have some questions? Let's discuss.