First, you have to complete an online questionnaire.
Next, you have to schedule a mock interview.
The mock interview takes two hours and you will be talking live with a person conducting the interview.
Build a Trello-like dashboard
You will be asked to build a Trello-like dashboard from scratch. MAKE SURE YOU REVIEW A TUTORIAL and complete a Trello-like dashboard tutorial in React, etc., BEFORE you take the interview.
You will be asked to complete a number of precise steps to complete the dashboard. You do not have the freedom to just do whatever you want. There is a guide to follow. You will be sharing your computer screen with the person interviewing you.
DO NOT USE Foundation, Bootstrap, Bulma, etc. A normalize stylesheet would help just to have a clean slate to begin with.
DO USE something like React, Angular or Vue. Set it up ahead of time on your computer, not on some online sandbox.
Do you know CSS Grid? Do you know Flexbox? Do you know your way around CSS?
YOU WON'T HAVE MUCH TIME. Make sure that you address the questions/steps presented and nothing else! Do not try to do anything outside of the steps needed. I repeat, stay on track. STAY ON TRACK.
How do you structure the components needed? Are you consistent in your naming choices? Are you making a mess in a few minutes? Do you know how to pass data around components? Did you complete the steps in the time given or wasted your time because you did not know what you were doing? You need to complete step 1 before you complete step 2 and so on. The complexity increases as you progress but you will do fine if you focus ONLY on the steps given.
KEEP THE SOLUTION ELEGANT.
Best thing again is to take one or two tutorials (or a dozen if you have time) and understand the steps taken to accomplish a similar Trello-like dashboard.
Functional Programming
Do you know what Immutability is all about? Study this before the interview. Review what you know about functional programming in general.
OOP
Just review concepts on OOP.
Algorithms
Do you know what a binary search tree is? Be prepared to explain. Review your knowledge of Algorithms and Data Structures. Take a course/tutorial if you need to.
Imaginary Backend App
If you had a billion records to serve, how would you go about into building a database that supports such records? You can use an imaginary SQL database or an imaginary NoSQL database. Just make sure that you have a plan of action that makes sense.
Security
Do you know what an XSS attack is? Do you know what Cross-Site Request Forgery (CSRF) is? Review the most typical security vulnerabilities in a web application/website.
THERE IS A GUIDE GIVEN BEFORE THE TEST. So take the time to study the parts that they tell you they are going to be asking for.
Good luck.