How to intercept node.js express request

Question

You can do what you need in a couple of ways.

This will place a middleware that will be used before hitting the router. Make sure the router is added with app.use() after. Middleware order is important.

app.use(function(req, res, next) {
  // Put some preprocessing here.
  next();
});
app.use(app.router);

You can also use a route middleware.

var someFunction = function(req, res, next) {
  // Put the preprocessing here.
  next();
};
app.post("/api/v1/client", someFunction, Client.create);

This will do a preprocessing step for that route.

Note: Make sure your app.use() invokes are before your route definitions. Defining a route automatically adds app.router to the middleware chain, which may put it ahead of the user defined middleware.