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So since it seems to me that this article entirely failed to mention why the callback pattern was harmful could someone else?

• erjiang 12y ago
  I've described some in the post I linked at the beginning, and many many others have described similar things. I've cribbed these from TJ Holowaychuk's recent post and added some others: * callbacks are not logical for expressing sequential logic * you end up with deeply nested code when having many sequential actions * you may get duplicate callbacks * you may not get a callback at all (lost in limbo) * you may get out-of-band errors * emitters may get multiple “error” events * missing “error” events sends everything to hell * often unsure what requires “error” handlers * “error” handlers are very verbose * callbacks suck * too many different libraries to "fix" callbacks that each have their own problems * e.g. easy to lose errors in Q promises * varying performance of various promises/async libraries * "best" async library constantly changes * callback style is the only common api, so you end up with wrappers for each library x library combination * sometimes forget whether a function uses a callback, returns a promise, is a generator, returns a stream, returns something that looks like a promise * some libraries may not call callback asynchronously and more. Callbacks have gotten a reputation as a dead horse that people like to beat on.