This is brilliant! For me I always want space after comma, and frequently put it there myself after a Join Line.
I've reworked it a bit to fix a couple of small bugs and to add some more characters. Now the following sets will have a space added after a join line: && || , : ; { ) and an opening brace gets a space before it. So a few joins will change this:
if (true && test(1, 0) || foo ) { // Code } else { // Code }
Into this:
if (true && test(1, 0) || foo) { // Code } else { // Code }