How to prepare for Web Developer Interviews?

Heard these names? Kylie Simpson / Dan Abrahomov / Douglas Crockford? Your job is half done if you are passionate about how Javascript works. Learn Javascript. It is the most crucial part. After giving ample of web interviews and even mentoring college undergraduates on JS, I think I can write about this now. Before any interview, I broke down my preparation under 5 roofs :

1. JS Core concepts: Closures, Scoping, Execution Context, Hoisting, Event loop, Async JS, Promises, Callbacks, Prototypes, Objects and everything on how Javascript works until you get a clear picture of what happens behind the scene. You should be very comfortable with how any code snippet of JS works internally. Once you understand how Execution context works, every weird thing in JS starts making sense.

2. Coding JS: Start by implementing some common libraries like map, filter and every day to day functions you use. You should know how common ES6 features can be implemented using plain JS. Examples: Arrow functions, Classes, bind, call, apply. Code all the common DS Algo questions in JS ( Tree / Array / LinkedList / Recursion ). Basics of DS Algo would be enough for your interview. There is no DS Algo problem that you cannot solve with Javascript. Your language preference should always be JS when it's a Web Dev role.

3. Web Optimisations: This is a crucial thing upon which you will be judged. Some important optimization techniques - Critical rendering path, Debouncing, Throttling, Lazy loading, List virtualization. Remember the second point, you should be comfortable writing code from scratch for any of the above techniques. Google dev has a good set of docs on Web fundamentals and optimization techniques. This resource would be enough to get you prepared: https://developers.google.com/web/fundamentals/.

4. Javascript Design Patterns: Most people ignore this but learning some of the common JS design patterns makes you write professional and scalable code and that's an impressive skill to showcase to any interviewer. Practice some common ones like Constructor, Module, Observer, Pub-sub pattern. These will also help you in understanding closures well and how closures build up most of the things in JS. Having them in your skills is a great add-on. Resource : Book by Addy Somani on JS design patterns.

5. HTML + CSS + Browser: Though most of the interview might revolve around JS, you should never take CSS too lightly. Understanding CSS is tough. So, you should know how cascading, layout-ing, specificity, responsiveness and rendering work. You might be given a scenario to adjust some content on a page using CSS. Initial containing block, Layout and positioning should be given importance. I repeat you can screw your interview if you don't understand how browsers and CSS work. The best place to learn is MDN or Mozilla web docs.

Note : If you can read a book, read "You Don't know JS" by Kylie Simpson but I will recommend it only after a few days of practice.

I have seen a very common thing in all web developers- They are passionate about Javascript. Your ultimate method should be to practice till the time you love writing anything in JS.

All the best for your interviews !!!