1 Essential Express.js Interview Question*

What function arguments are available to Express.js route handlers?

The arguments available to an Express.js route handler function are:

  • req - the request object
  • res - the response object
  • next (optional) - a function to pass control to one of the subsequent route handlers

The third argument may be omitted, but is useful in cases where you have a chain of handlers and you would like to pass control to one of the subsequent route handlers, and skip the current one.

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* There is more to interviewing than tricky technical questions, so these are intended merely as a guide. Not every “A” candidate worth hiring will be able to answer them all, nor does answering them all guarantee an “A” candidate. At the end of the day, hiring remains an art, a science — and a lot of work.
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Michael Cole
United States
Michael is a full stack developer who creatively balances usability with business objectives. He is an excellent JavaScript developer (API design, implementation, and security with Node.js, Express, NoSQL, and SQL) with front-end (AngularJS) and integration (Stripe.js, Passport.js) experience.
Luuk van Egeraat
Netherlands
Luuk is a Dutch web developer working on high-performance, modern web applications with advanced front-end functionality. He also advises companies on the implementation of abstract business ideas by creating prototypes. He has created a variety of web applications for multiple large companies.
Johan Hernandez
Colombia
Johan is a mobile app and cloud back-end developer with over 15 years of experience. He's been telecommuting for startups in the USA since 2010. He has worked with enterprise stacks for a number of years, but more recently his primary focus has been on building native apps for mobile and desktop (Mac, iOS, Android and Windows) using Swift, Objective-C, Java, Kotlin, and C#. He also builds his own RESTful back-ends with Rails, Node, and Golang.