2.4.0

• Experimental support for vert.x 2.x. Should now run in vert.x >= 1.1.0. (#183)
• New when.isPromiseLike as the more accurately-named synonym for when.isPromise. (#161)
• DEPRECATED: when.isPromise. It can only tell you that something is "promise-like" (aka "thenable") anyway. Use the new, more accurately-named when.isPromiseLike instead.
• Fix for promise monitor reporting extra unhandled rejections for when.all and when.map. (#186)

2.3.0

• New promise.tap for adding side effects to a promise chain.
• New MessageChannel scheduler reduces "time-to-first" handler, in environments that support it.
• Performance optimizations for promise resolution.
• Internal architecture improvements to pave the way for when.js 3.0.0.

2.2.1

• Fix for when.defer().reject() bypassing the unhandled rejection monitor. (#166)
• Fix for when/function, when/callbacks, and when/node/function not preserving thisArg. (#162)
• Doc clarifications for promise.yield. (#164)

2.2.0

• New experimental promise monitoring and debugging via when/monitor/console.
• New when.promise(resolver) promise creation API. A lighter alternative to the heavier when.defer()
• New bindCallback and liftCallback in when/node/function for more integration options with node-style callbacks.