Full-Stack Web Development

DNS lookup, TCP/TLS connection, HTTP request, server response, then the browser parses HTML, loads CSS/JS, builds the DOM/CSSOM, lays out and paints the page.

var is function-scoped and hoisted; let and const are block-scoped. const cannot be reassigned (though objects it holds can be mutated). Prefer const, then let.

React keeps a lightweight representation of the UI, compares (diffs) it after state changes and applies only the minimal real DOM updates needed.

Client-side rendering builds the page in the browser; server-side rendering builds HTML per request on the server; static generation builds HTML at build time. SSR/SSG improve SEO and first load.

A browser security mechanism that blocks cross-origin requests unless the server explicitly allows the requesting origin via response headers.

REST exposes resources at multiple endpoints with fixed responses; GraphQL exposes one endpoint where clients request exactly the fields they need. GraphQL reduces over-fetching but adds complexity.

Never store plain text. Hash with a slow, salted algorithm like bcrypt or Argon2, and use HTTPS everywhere.

A data structure that speeds up lookups on columns at the cost of extra storage and slower writes. Index columns used in frequent WHERE, JOIN and ORDER BY clauses.

The mechanism that lets single-threaded JS handle async work: the call stack runs code, and completed async callbacks wait in task/microtask queues until the stack is empty.

Measure first (Lighthouse, Web Vitals), then optimise images, reduce/split JS bundles, cache responses, use a CDN, lazy-load below-the-fold content and fix slow API queries.