Frontend Engineer

Browser APIs & Storage

Vì sao: Lets you cancel a stale search request with AbortController or persist a draft in storage, instead of showing outdated results or losing the user's work on refresh.

Web Security (CORS/CSP/XSS)

Vì sao: Lets you render user-supplied content and call another origin without opening an XSS hole or a CORS error that blocks the release.

Component Design Patterns

Vì sao: Lets you extract hooks and compound components so a second team can reuse a feature you built, instead of forking it and drifting apart.

State Management Strategies

Vì sao: Lets you decide what belongs in local state, the URL or a server cache, so a filter survives a page reload and the same data is not fetched in three places.

Core Web Vitals (LCP/CLS/INP)

Vì sao: Lets you read a field report showing a slow LCP or layout shift on real phones and trace it to a specific image or late-loading banner.

Bundle Optimization & Code Splitting

Vì sao: Lets you find why the first load grew after a new dependency and fix it with route-level code splitting, instead of shipping the whole app to every visitor.

Unit Testing (Jest/Vitest)

Vì sao: Lets you cover a date formatter or price calculation with fast tests, so a refactor of that utility fails in CI before it reaches a customer invoice.

Component Testing (Testing Library)

Vì sao: Lets you test a form the way a user uses it, by label and role, so a harmless markup change does not break the suite while a real regression still does.

Build Tools (Vite/Webpack)

Vì sao: Lets you fix a build that works locally but fails in CI, or tame a slow dev server, because you understand what the bundler and its env variables do.

TypeScript in Frontend

Vì sao: Lets you type props and API responses so a backend field rename shows up as a compile error in your editor instead of a blank screen in production.