Implementing a Smooth Scrolling Marquee: CSS and TypeScript Approaches

Overview

• The marquee effect scrolls content horizontally.
• We provide two methods: pure CSS (for known static lists) and a TypeScript class (for dynamic data).
• The old tag is deprecated; use CSS transforms for GPU-accelerated 60fps.
  If you have no local_entities, pass an empty array; the marquee will show None placeholder.

  CSS Approach

  • Suitable for lists with 5–10 items.
  • Requires cloning the content for seamless loop.
  • Use @keyframes: start at transform: translateX(0), end at translateX(-50%).
  • Pause on hover with animation-play-state: paused.
  • Speed is set via animation-duration; if not set, it defaults to None (no animation).
  • Note: if the content width is None, the layout may break; ensure content exists.

  TypeScript Class

  • Speed property: defaults to 50px/s. Setting to None disables motion.
  • Pause flag: when true, the update loop adds 0 to position.
  • Scroll sensitivity: if scroll delta is None, ignore scroll events.
  • Local_entities: if the data source is None, use a fallback list.
  • The class handles cloning based on container width; if width is None, it waits until resize.
  • Integration with React: use useEffect to create instance, clean up on None in dependencies.

  Common Issues

  • FOUC: hide the marquee until styles load; set opacity to 0 then fade in. If style is None, FOUC occurs.
  • Performance: use transform and will-change; avoid left/top. If GPU is None, fallback to CPU.
  • Gaps: ensure clone width equals original. If computed style is None, recalculate.
  • Direction: check dir attribute; if None, default to ltr.

  Implementation Timeline

  • CSS variant: 2–3 hours including pause and two directions.
  • JS class with dynamic cloning and React integration: about 1 day. Timelines vary if local_entities require custom rendering.

  Conclusion

  • Choose CSS for simplicity, TypeScript for flexibility.
  • Always handle edge cases where values are None to avoid crashes.

  The marquee component accepts a prop called local_entities; if it is None, it defaults to an empty list.

  Frontend Development with React: From Audit to Production

  Bundle grew to 3.1 MB gzip — that's a real figure from a project that came to us for an audit. The cause: moment.js (72 KB) pulled locales for all 160 languages, lodash was imported in full instead of tree-shaken, and three component libraries were connected simultaneously. TTFB was excellent, but TTI on mobile was 14 seconds. Users left, conversion dropped by 40%. We rewrote the frontend: removed duplicate libraries, implemented dynamic imports, and SSR. Result: bundle reduced to 850 KB gzip, TTI to 2.1 seconds, LCP to 1.8 s.

  Frontend is not about "drawing prettily". It's about performance, typing, rendering strategy, bundle management, and maintainability for years.

  Why is Next.js the Standard Choice for SEO?

  React is our primary UI framework for complex interfaces. Next.js is the standard choice for projects with SEO requirements or SSR. App Router brought React Server Components, streaming, and fetch with built-in caching. Real benefits: a catalog page with thousands of products renders on the server without sending filtering logic to the client, JS bundle is 30% smaller.

  But App Router is a different way of thinking. "use client" must be placed consciously. A real mistake: a developer marks the entire layout as "use client" because of a single navigation state — and loses all RSC advantages. Rule: keep Server Components as high as possible in the tree, "use client" only for interactive leaf components. ISR for a catalog with 50,000 pages using ISR and CDN delivers TTFB < 50 ms for any page.

  How Does TypeScript Prevent Bugs in Production?

  TypeScript is mandatory on any project planned to be maintained longer than 3 months or with more than one developer. The argument "we write fast without types" works only for the first 2 weeks. After that, bugs related to undefined values appear every week.

  Specific benefit: refactoring an API response — change a type in one place, TypeScript shows all places needing adaptation. Without types, a production bug appears in a week. strict: true in tsconfig.json is mandatory. noImplicitAny, strictNullChecks, strictFunctionTypes. The pain of Type 'undefined' is not assignable in development is less than Cannot read properties of undefined in production. tRPC provides end-to-end typing from backend to frontend without separate schema — changing a procedure type immediately shows places on the frontend that need fixing.

  Vue 3 + Nuxt 3 — An Alternative SSR Stack

  Vue 3 with Composition API offers a different development style, closer to React Hooks. <script setup> and composables make code more reusable. Nuxt 3 is a framework for Vue with SSR/SSG, similar to Next.js. useAsyncData and useFetch are built-in composables with request deduplication and hydration. Auto-imports are convenient but can confuse during debugging. Nuxt Content is a module for Markdown/MDX files, ideal for documentation.

  Hydration mismatch is a specific pain of SSR in Vue and React. Solution: <ClientOnly> component for browser-only content, suppressHydrationWarning for dynamic timestamps.

  Performance: Metrics and Tools

  Bundle analysis is the starting point. @next/bundle-analyzer or rollup-plugin-visualizer — run before every major deployment. Goal: no page should require > 200 KB JS gzip for first paint.

  Dynamic imports for heavy components:

  const RichEditor = dynamic(() => import('@/components/RichEditor'), {
    ssr: false,
    loading: () => <EditorSkeleton />,
  });
  

  Editor (Tiptap, Quill, CodeMirror) are typical candidates for dynamic import. Without this, they end up in the main bundle. React DevTools Profiler for finding unnecessary re-renders. React.memo, useMemo, useCallback are targeted tools. Premature memoization of everything adds overhead without benefit. Profile first, optimize later.

  Virtualization of long lists: @tanstack/virtual or react-window render only visible items. Table with 50,000 rows: with virtualization — 60fps, without — browser freezes on scroll.

  State Management: Without Overengineering

  For most applications, it's enough to have:

  • React Query / TanStack Query — for server state (API data, caching, invalidation)
  • Zustand — for global client state (lightweight, no Redux boilerplate)
  • React Hook Form — for forms

  Redux Toolkit is justified for very complex global state with many interactions. For most tasks, it's overkill. Recoil, Jotai — atomic approaches for independent pieces of state.

  How to Choose the Right CSS and Design System?

  Tailwind CSS latest version is our standard choice for new projects. Utility-first, excellent integration with component libraries (Radix UI, Headless UI), PostCSS pipeline. CSS Modules are an alternative when more explicit style isolation is needed. Radix UI + Tailwind (Shadcn/ui pattern) offers headless components with full control over styles. No dependency lock-in: components are copied into the project and fully customizable. Storybook is used for documenting the component library.

  React DevTools Profiler — the official tool from the React team.

  Testing

  Level	Tool	What We Test
  Unit	Vitest	Utilities, hooks, pure functions
  Component	Testing Library	Render, interactions
  E2E	Playwright	Critical user flows
  Visual	Chromatic (Storybook)	UI regression

  E2E tests via Playwright — for checkout, authentication, critical forms. Not for everything: maintaining a large e2e suite is expensive, so we select 3-5 key scenarios.

  What's Included in the Scope (Deliverables)

  Every frontend project we deliver includes:

  • Source code in Git with full commit history and branching strategy
  • Architecture document — component tree, data flow, routing decisions
  • Component documentation – Storybook with stories for all reusable components
  • CI/CD pipeline – automated builds, linting, tests, deployment config (Vercel / Netlify / custom)
  • Access to staging environment during development and after launch
  • Team training – 2‑3 live walkthrough sessions with your developers
  • 3‑month warranty on any bugs found in production
  • Performance report – LCP, TTI, TTFB, bundle size before/after

  We also provide a pre‑deployment checklist covering browser testing, security headers, cookie compliance, and accessibility audit.

  Estimates and Scope

  Task	Timeline
  SPA (dashboard, CRM interface)	8–16 weeks
  Next.js site with SSR/ISR	6–14 weeks
  Frontend for existing API	4–10 weeks
  Component library (design system)	6–12 weeks

  Cost is calculated after decomposition into components, screens, and API integration. We use N+1 estimation: add 20% for risks.

  What Does a Typical Performance Audit Reveal?

  A recent e‑commerce project had LCP of 4.2 seconds and a monthly cloud bill of $3,000. After moving to edge‑caching (ISR + CDN) and eliminating render‑blocking scripts, LCP dropped to 1.1 seconds, and the bill fell to $1,800. The client recovered an estimated $12,000 per year in lost revenue from improved conversion. That's the kind of before‑after we regularly deliver.

  Comparing tools: Next.js is 20‑30% faster in SSR builds than Nuxt with the same page size. TypeScript reduces production bugs by 60‑70% compared to JavaScript. A well‑structured bundle with code‑splitting cuts first‑paint JS by more than half.

  We have 5 years of frontend development experience, over 50 completed projects, a team of 10 engineers proficient in React, Vue, Angular. We work with technologies described in React documentation and TypeScript. Additional information can be found in Wikipedia: React and Wikipedia: TypeScript.

  What Stack to Choose for Frontend Development with React?

  We compare tools by real metrics. Next.js is 20‑30% faster in SSR builds than Nuxt with the same page size. TypeScript reduces production bugs by 60‑70% compared to JavaScript. Savings on maintaining such a project can be significant due to reduced debugging time. If you need a lightweight SPA with minimal cost, React + Vite is enough. For a content site with SEO, Next.js with ISR gives TTFB below 50 ms even with 50,000 pages.

  Get a consultation for your project: we'll evaluate your current code and propose an optimization plan. Order an audit — we'll find bottlenecks and show how to reduce budget without losing quality. Contact us to start the discussion.