Hoisting in javascript along with global variable

Question

The below code gives an output of undefined. I was of the impression that all variable and function declarations are hoisted to the top of their scope and so b should now be at the top the scope before calling a(). However, I still get undefined as my output?

a()

var b = 5;
function a() {
  console.log(b)
}

Answer 1

You misunderstand how hoisting works. It doesn't hoist the assignment, it only hoists the declaration. Your code is equivalent to the following:

var b; // undefined
function a(){
 console.log(b)
}
a();
b = 5;

Answer 2

Yes the variable declaration is hoisted, but the value is not set on b. The code looks like this

var b
function a(){
 console.log(b)
}
a()
b = 5;

Answer 3

Hoisting means the variables will be created “at the top” - but it does not change anything about the time the value assignment happens, the b = 5 part still happens when execution reaches the part where it’s written. So if you call a() before that, b exists, but has not gotten any value assigned yet … hence, undefined

Answer 4

You are using a function declaration to create a function. So function declaration is also hoisted so they are being used before declaring.