Hoisting

Hoisting is the default behavior of javascript where all the variable and function declarations are moved on top during the compilation phase.

There are two main aspects of hoisting:

1. Variable Hoisting: Variable declarations using var are hoisted to the top of their scope, but their assignments are not. This means that you can use a variable before it’s declared without causing a syntax error, although its value will be undefined.

console.log(myVar); // Output: undefined
var myVar = 42;

2. Function Hoisting: Function declarations are also hoisted to the top of their scope. This means you can call a function before it’s defined in the code.

myFunction(); // Output: "Hello, world!"
function myFunction() {
  console.log("Hello, world!");
}

It’s important to note that variable declarations using let and const are also hoisted, but they are placed in a “temporal dead zone” where they cannot be accessed until their declaration is encountered in the code. This prevents you from accessing variables before they’re properly initialized, which is a common source of errors.