ifthen: support if/then/else/finally branch logic in Javascript callbacks ifthen.if_(/* condition */) .then_( // required, called if `condition` function (callback) { // callback must be called to trigger completion callback(); }) .else_( // optional; called when `! condition` // cannot be specified unless `then_` is function (callback) { // callback must be called to trigger completion callback(); }) .finally_( // optional, always called after branch completes function (err) { // } );