What does the unary plus do here?

Question

JavaScript

Two essentially identical codes:

+function() {
  alert('Вызов на месте');
}();

(function() {
  alert('Вызов на месте');
}());

Why does the first code work? What does the unary plus do?

Answer 1

Plus indicates that this is a Function Expression and not a Function Declaration. Parentheses do the same.

Answer 2

In the second example, the parentheses are wrong, it should be like this:

(function() {
  alert('Вызов на месте');
})();