A recruiter reached out on LinkedIn and kicked off the process with a quick 20-minute screen. This covered basic topics like past frontend work, JavaScript depth, and interest in Meta.

The first tech round was phone-based and focused on core JavaScript concepts such as closures, asynchronous programming, and array/object operations, along with some quick CSS and HTML. The emphasis was on clean, real-world problem-solving.

The onsite portion consisted of three rounds:

• Two rounds were coding-heavy, requiring the writing of JavaScript functions for tasks like flattening nested arrays, building a DOM from JSON, and recursion. While not "LeetCode hard," structured thinking was crucial.
• The third round focused on frontend system design, involving scenarios like building a messaging UI or a dashboard. The goal was to assess architectural skills, performance considerations, and user interaction thought processes.
• The final round was a mix of light HTML/CSS coding and behavioral questions, such as debugging stories or discussing past UI challenges.

My preparation involved using Prepfully mocks (which were super helpful), brushing up on raw JavaScript, DOM APIs, Big O notation, and UI-specific data structures. They seemed to value solid fundamentals and clean decisions over flashy techniques.

I received an offer. My advice to others would be: know your tradeoffs, talk through your thought process clearly, and avoid overcomplicating your code.

How would you architect the frontend for a messaging system?