what is hosting

What is Hoisting?

Hoisting is JavaScript's default behavior of moving declarations (not initializations) to the top of their scope (global or function) during the memory creation phase.

In reality, nothing is physically moved.
It’s just that variable and function declarations are stored in memory before code execution starts.

---

How Hoisting Works

JavaScript executes code in two phases for each execution context (Global or Function):

1. Creation Phase (Memory Allocation)

   • Variables (var) are hoisted with value undefined.

   • Functions (function declarations) are hoisted with their full definition.

2. Execution Phase

   • Code runs line by line.

   • Variable assignments happen here.

---

Examples

1. Hoisting with var

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

Why undefined?

• During creation phase: x = undefined.

• During execution: x = 5.

---

2. Hoisting with Functions

greet(); // Hello!

function greet() {
    console.log("Hello!");
}

Works fine because the entire function is hoisted.

---

3. Function Expression (Not Hoisted Like Declarations)

greet(); // TypeError: greet is not a function

var greet = function() {
    console.log("Hello!");
};

Here, only the variable name greet is hoisted as undefined, not the function body.