Dealing with asynchronously initialized components

One of the reasons for the existence of synchronous APIs in the Node.js core modules and many npm packages is because they are handy to use for implementing initialization tasks. For simple programs, using synchronous APIs at initialization time can streamline things a lot and the drawbacks associated with their use remain contained because they are used only once, which is when the program or a particular component is initialized.

Unfortunately, this is not always possible. A synchronous API might not always be available, especially for components using the network during their initialization phase to, for example, perform handshake protocols or to retrieve configuration parameters. This is the case for many database drivers and clients for middleware systems such as message queues.

The issue with asynchronously initialized components

Let's consider an example where a module called db is used...