foo.js

// not sure I like: 
!function(a, b){ /* ... */ }(1, 2);
// over:
(function(a, b){ /* ... */ })(1, 2);

never seen the first one. based on general knowledge, i'd say the second is best. The bash symbol reminds me of ruby's function implication meaning you're going to be altering the object in question immediately, so I suppose it's appropriate here (firing immediately).

i see it as trading readability for a single byte saving. The ! to me means "not", at least in js. The latter example reads to me: "this wrapped function" then "execute with these args passed".

seeing

... }(1, 2)

hurts my brain.

agreed.