June 2025
Intermediate to advanced
837 pages
24h 50m
English
A key design feature of Express is the middleware concept, which makes the framework a very flexible tool. Simply put, middleware here refers to a function that stands between the incoming request and the outgoing response. You can put as many of these functions in succession as you like. There are already numerous predefined middleware functions that you can include in your application and that perform specific tasks for you. If all this doesn’t provide any solution to your problem, you can even write such a function yourself.
You can use a middleware function to extract information from the incoming request and store it, such as with a logger. However, you can also enrich the response based on information ...
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