Comparison

At this point, we should have a better understanding of the options we have to tame the asynchronous nature of JavaScript. Each one of the solutions presented has its own pros and cons. Let's summarize them in the following table:

Solutions	Pros	Cons
Plain JavaScript	Does not require any additional libraries or technology Offers the best performance Provides the best level of compatibility with third-party libraries Allows the creation of ad hoc and more advanced algorithms	Might require extra code and relatively complex algorithms
Async (library)	Simplifies the most common control flow patterns Is still a callback-based solution Good performance	Introduces an external dependency Might still not be enough for advanced flows
Promises	Greatly simplifies the most common control flow patterns Robust error handling Part of the ES2015 specification Guarantees deferred invocation of onFulfilled and onRejected	Requires promisify callback-based APIs Introduces a...