Why JavaScript functions always return a value?

Question

I\'m taking a course in JavaScript programming, and the instructor said that a typical JavaScript function always returns a value. Even when we don\'t provide any explicit r

Answer 1

That's by ECMAScript specification

13.2.1 [[Call]] ... 6. Otherwise result.type must be normal. Return undefined.

Essentially any JS function is compiled as if it has implicit return undefined; at the end:

function foo() {
  ...

  return undefined; // implicit non-visible statement  
}