Senior is not about knowing more APIs. It is about making decisions others can build on: structuring large codebases, designing systems, weighing trade-offs, and raising the level of the whole team.
Feature-based folder structure, separation of UI and logic, module boundaries, design patterns, and writing architecture decision records.
Designing systems like a news feed, chat, autocomplete, or editor: requirements, component architecture, data model, API, performance, and accessibility. A standard senior interview round.
Translations, plurals, locale-aware formatting with Intl, RTL layouts, and localised routing and SEO.
Sharing code across apps with pnpm workspaces, Turborepo, or Nx, and when micro-frontends are worth their complexity (rarely).
Reviewing code kindly and usefully, mentoring juniors, estimating work, writing clearly, and explaining technical trade-offs to non-engineers.
You can own a frontend codebase end to end and help other developers grow.
Stage project
Write a frontend design document for a feature like a collaborative editor or an e-commerce checkout.
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