Is this a syntax sugar for iife?

[lxe]

let x = do {
  if (foo()) { f() }
  else if (bar()) { g() }
  else { h() }
};

Can be expressed as

let x = (() => {
  if (foo()) { return f() }
  else if (bar()) { return g() }
  else { return h() }
})();

Right?

[ljharb]

The IIFE case can’t return from the enclosing function, and creates an extra frame on the stack (ie, if an error is thrown), and vars defined within it wouldn’t be available outside the expression.

[lxe]

Thanks for the explanation @ljharb I ... didn't think of the block scope preservation.