JavaScript - hoisting

With JavaScript hoisting, or since JavaScript hoist variables, variables can be used before declaration.

So even if you call a function, before it is declared, you can still get the same result as when you call the function after its declaration.

sayHello(); // "hello"

function sayHello() {
  console.log("hello");
}

sayHello(); // "hello"

So even if you call a function before its declaration, you won’t get undefined. JavaScript hoist declartaion, but it won’t hoist initialization.

a = 3;
console.log(a); //  3
var a;

console.log(b); // undefined
var b = 3;