##What are middleware functions?
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Middlewares are functions that handle an incoming HTTP request. That is, whenever a browser makes a request to your website (e.g. a reload or password submit), the request is processed through all the middleware functions and eventually a response is sent back to you.
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Essentially, an express server is a stack of middlewares that a request can traverse through. The last middleware (technically called a response handler) sends a response back to the client (i.e. browser).
##How do I register a middleware function?
- Use
app.use(PATH, function(req, res, next) {/* Middleware function code goes here */} );-
PATH is just a string specifying for what requests the middleware should be used for. For example, for a path of '/hello', the middleware function would only be called when going to 'http://your_cool_domain_name.com/hello'.
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You can omit PATH and the middleware will be called for ALL requests. ##How are middleware functions processed?
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Middlewares are called in the order they are registered.
##What are some uses for middleware functions?