I do that sometimes (obviously not in JavaScript), to split up long lines in situations such as this:

  bool is_foo_possible() {
    return
      test_first_condition() &&
      test_second_contition() &&
      test_third_condition()
  }

I don't think that's very horrible.

I would tend to write that:

  bool is_foo_possible() {
    return test_first_condition()
      && test_second_contition()
      && test_third_condition()
  }

I prefer to put my infix operators at the beginning of continuation lines, because that makes it immediately clear from a glance that it's a continuation line.

I do this as well.

For a while, I tried to stick to the rule that "return\n" was not allowed. When I meant to return undefined, I'd write "return undefined".

In the end, I abandoned that rule, because too many of my functions return undefined. But it's kind of a nice thing. When I do get around to building that linter, I might make `return\s*\n` verboten.

You could just write "return;", that would make it obvious that no value is returned.

OH. Good point.