It is fairly common to see frameworks which want you to pass a very small javascript "object" as a parameter - witness node.js's http.request or node.js's mongodb driver.

It is annoying that reformat code breaks the formatting of small objects across lines - so this:

collection.update (query, data, {safe : true}, function (err, data) {
  ...
}

gets reformatted into much-less-readable:

collection.update (query, data, {
   safe : true
}, function (err, data) {
  ...
}

A simple heuristic which would get this right most of the time would be:
 - If the hash has 1-2 key/value pairs
 - If it is already on a single line
leave it alone,  otherwise reformat it.