What is hoisting in JavaScript?

What is hoisting in JavaScript?

Hoisting is a JavaScript mechanism where variables and function declarations are moved to the top of their containing scope during compilation.

Can you give me an example of hoisting with variables?

Sure! For example, if you declare a variable like this:

console.log(x); // undefined
var x = 5;

The output will be 'undefined' because the declaration is hoisted, but the assignment is not.

What about function hoisting?

Function declarations are fully hoisted. For example:

hello(); // 'Hello!'
function hello() {
  console.log('Hello!');
}

This works because the entire function is hoisted.

Are there any differences between var, let, and const in hoisting?

Yes! Variables declared with var are hoisted and initialized to undefined, while let and const are hoisted but remain uninitialized, leading to a ReferenceError if accessed before declaration.