Suddenly the errors are no longer inheriting from the same module but are two entirely independent objects in memory and therefore the instanceof check is about to fail.
Gitify resources code#
In the error case it is furthermore checking if the error is of a specific error instance (which live in our errors module) and running different code depending on the result.Ī typical problem with this approach can be seen when an application that uses this code and the module that allows reading content entries are running a different installation of the errors module – even though they might use the same version. The following code snippet is about reading an entry via a node module and about handling its success and error case. It is getting even worse if your code contains instanceof checks which makes it crucial to only ever have a single installation of a module. This is a good solution for smaller applications which only have small amount of modules, but it’s getting very frustrating when you have a lot of them, or if the module’s sub-modules are subject to change as well. Typically this is the time when you start cloning the module repository to some place and start doing the npm link dance, which allows you to inject npm modules - that are located somewhere else on your hard drive - into an application. So, while moving isolated logic into its own module generates a lot of advantages, it also makes it more complex to change them in the scope of the entire application and to ensure that such changes are not breaking the application. In order to prevent unpredictable breakages and problems with not-so-semver version bumps, we typically also have an npm-shrinkwrap file in place that pinpoints a specific version for every module and its sub-modules in the application. Additionally, we have modules which bundle all kinds of validations or contain all kinds of error codes and are therefore used in almost every application. For example we have a library that is connecting our apps to a shared logging system, or to an exception tracker, or to new relic, or to… you get the idea. Also the same modules are used in various places. All of them are using various node modules that are either publicly available or hosted privately.
At Contentful we have various JavaScript applications that are running in the browser or are powering the backend.
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