System Design Q&A and Videos

I have been working for small companies for the past 5 years where the focus was on shipping the product fast and not necessarily on quality. I am now interviewing at big tech companies where the focus is on code quality and code scalability. I am concerned that even if I make it through the interview phase it will be hard for me to maintain my position after having bad coding practices for many years.

How can I get started in learning how to write clean, reusable and scalable code? I work primarily with JavaScript and Java. Can you point me to some resources to learn how to improve my code and apply best practices that will make me a great engineer? I am familiar with concepts like DRY, SOLID principles but I am looking for something actionable not some abstract concept.

I have been wanting improve my technical understanding on what I am working on:

• Since there's so much happening in the backend, frontend and database levels, it can get intimidating to try and see how it all makes sense, when it all feels chaotic trying to put everything together.
• I feel that the one thing that could help me progress to the senior level is to better my technical influence, and I was wondering how I can improve on that.
• I have been proactively speaking with senior engineers and the architect involved with the new feature that's being worked on. That has really helped me better my understanding on what I'm working on. But when it comes to the code, it can be challenging since there are so many files that depend on one another, and I feel that I would need to spend a couple hours a day just understanding how each of those code files work.

What other steps can I take to enhance my technical influence, and then reach that senior level?

I'm not sure exactly how to phrase this, but to give an analogy, I love card games (ex: Legends of Runeterra, Race for the Galaxy, Hearthstone, etc). There are a fixed set of rules and a fixed set of cards. I can "grind" games and get better by noticing patterns, picking up new strategies or tactics by playing against a diverse set of players. The outcome of an interaction is usually idempotent (i.e. card 1 interaction with card 2).

In real life, things are quite complicated. Asking a certain question in a certain way to person 1 and person 2 may give wildly different responses, and may even depend on your mood, their mood, your tone, time of day, etc. It's super messy and unpredictable.

I also feel a similar way about system design. The nearly infinite possibility of inputs, outputs, TPS, throughput, scenarios make it difficult to reapply the same set of rules to different scenarios. This is just talking about one component, when we bring in N components, the interaction gets very complicated and the "rules" change" case by case. I'm sure it gets better with practice, but I also feel I have a limited opportunity to learn or practice these on the job.

Has anyone found a way to structure these learnings in terms of a repeated "grind", because oftentimes I feel overwhelmed and don't know where to start. This is a complicated question, so answers regarding either a) soft skills or b) system design separately I will treat as valid answers.

I am good at coding, and I am able to deliver features to prod. However, when it comes to technical writing, like writing software design document, coming up with state transition diagram, block diagram, I am struggling with it a lot. I am not from computer science background, so I am not well versed in coming up flow chart, sequence diagram and state transition diagram. How to improve on these areas? Because of this, I am finding it difficult to communicate my idea to principal engineers/ architects. How can I improve on this?

I am looking for some good books or detailed courses on system design which are targeted for Mobile engineers specifically.

What skills are essential for becoming a proficient software engineer which helps them to thrive in any tech domain and adapt to various situations?

Could you provide a list of items that one should be mindful of to excel in real-time scenarios? For instance, focusing on learning front-end and back-end development, knowing basics of web something like that.