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JavaScript User Authentication With Express and Mongo Improving the App with Custom Middleware Writing Custom Middleware

Why no params when calling mid.loggedOut ?

When we call the mid.loggedOut(req, res, next) function in our route, why is it that we dont need to pass the parameters, like:

router.get('/login', mid.loggedOut(req, res, next), (req, res) => { // route });

1 Answer

Hi Oliver,

There are no parameters because mid.loggedOut is not being called. If you look closely, you'll see that there are no parentheses after mid.loggedOut. All that's happening is that we're passing the function itself as a parameter, as a middleware. Express β€” the framework β€” is the one that ends up calling mid.loggedOut and as it calls it, it'll be the one that provides req, res, next parameters. Let me know if that didn't make sense.

Yes that makes sense :) Thank you for your answer.