What is Hoisting?

Hoisting is a JavaScript mechanism where variables, function declarations, and classes are moved to the top of their scope before code execution. Remember that JavaScript only hoists declarations, not initialization. Let's take a simple example of variable hoisting,

console.log(message); //output : undefined
var message = "The variable Has been hoisted";
The above code looks like as below to the interpreter,

var message;
console.log(message);
message = "The variable Has been hoisted";
In the same fashion, function declarations are hoisted too

message("Good morning"); //Good morning

function message(name) {
console.log(name);
}