Local and global scope

Question

var a = 1

function b() {
  a = 20
  return

  function a() {}
}
b()
console.log(a)

I thought the output would be 20 but its 1 ? The execution context of function b would access variable a from the GEC and update its value imo. Why is it so?

Answer 1

function declarations declare a variable sharing the name of the function in the current scope (like var does) and are hoisted.

function a therefore creates a local variable a inside function b and is that that variable that you overwrite.

---

Some people prefer to use arrow functions with explicit variable declarations. That creates an error instead of having the behaviour that surprised you.

var a = 1

function b() {
  a = 20
  return

  const a = () => {}
}
b()
console.log(a)