Vanilla JavaScript Frontend: Fast Widgets and Animations

When your application bundle exceeds 2 MB and LCP goes beyond 3 seconds, the cause is often framework bloat. For embed widgets, animations, or browser extensions, Vanilla JavaScript becomes the only adequate choice. We have delivered over 30 projects without a single framework, ensuring LCP under 1 second and bundle sizes of 20–40 KB. The absence of a virtual DOM and direct access to browser APIs provide maximum performance, while development budget savings reach up to 40% (up to 50,000 RUB on a typical widget). Our team leverages modern language features: Web Components, IntersectionObserver, Proxy, and ESModules to build fast and reliable solutions. Every project starts with metric auditing and selecting the optimal architecture. Contact us for a project audit.

When Vanilla JS Is the Only Right Choice

Vanilla JS is justified in scenarios where frameworks add unnecessary complexity. Embed widgets are inserted into third-party sites — they must not conflict with the host's frameworks. Libraries on npm with zero dependencies do not bloat users' projects built with different stacks. High-load animations use Canvas API, WebGL, and Web Animations API directly, without a virtual DOM layer. Browser extensions run in the isolated environment of Content Scripts, where frameworks increase risks. Static sites with minimal interactivity do not need 50 KB for a single dropdown. A typical Vanilla JS widget costs 30-50% less than its React counterpart.

In one project, we replaced a React cart widget with Vanilla JS. The bundle shrunk from 120 KB to 28 KB (a 77% reduction), LCP dropped from 2.4 s to 0.8 s (67% faster). CPU load decreased by 40%. Vanilla JS loads twice as fast as React on slow connections, and development savings amounted to about 40,000 RUB.

Why Vanilla JS Outperforms Frameworks

The absence of a virtual DOM eliminates overhead from diffing and re-rendering. Direct work with document.createElement and appendChild allows manual control over every update. Combined with IntersectionObserver for lazy loading and requestAnimationFrame for animations, you get LCP under 1 second even on mobile devices. We also use preload for critical resources and prefetch for subsequent pages. Bundle reduction of 77% and development budget savings up to 40% are common when migrating to pure JS.

What Modern Vanilla JS Can Do

Browser APIs have expanded significantly: now you have Custom Elements, Shadow DOM, AbortController, Proxy, and Service Workers. Example fetch with timeout:

async function fetchWithTimeout(url, options = {}, timeoutMs = 5000) {
  const controller = new AbortController();
  const timeout = setTimeout(() => controller.abort(), timeoutMs);

  try {
    const response = await fetch(url, { ...options, signal: controller.signal });
    if (!response.ok) throw new Error(`HTTP ${response.status}`);
    return await response.json();
  } finally {
    clearTimeout(timeout);
  }
}

Web Components — a component model without a framework

class ProductCard extends HTMLElement {
  static get observedAttributes() { return ['product-id']; }
  connectedCallback() {
    this.#render();
    this.#attachEvents();
  }
  attributeChangedCallback(name, oldVal, newVal) {
    if (name === 'product-id' && oldVal !== newVal) {
      this.#fetchProduct(newVal);
    }
  }
  async #fetchProduct(id) {
    const data = await fetchWithTimeout(`/api/products/${id}`);
    this.#update(data);
  }
  #render() {
    this.innerHTML = `
      <article class="product-card">
        <img class="product-card__img" alt="">
        <h3 class="product-card__name"></h3>
        <span class="product-card__price"></span>
        <button class="product-card__btn">Add to cart</button>
      </article>
    `;
  }
  #update({ name, price, image }) {
    this.querySelector('.product-card__img').src = image;
    this.querySelector('.product-card__name').textContent = name;
    this.querySelector('.product-card__price').textContent = `${price} RUB`;
  }
  #attachEvents() {
    this.querySelector('.product-card__btn').addEventListener('click', () => {
      this.dispatchEvent(new CustomEvent('add-to-cart', {
        bubbles: true,
        detail: { productId: this.getAttribute('product-id') }
      }));
    });
  }
}
customElements.define('product-card', ProductCard);

MDN: Web ComponentsUsage in HTML: <product-card product-id="42"></product-card>. Works in any framework or none.

Reactive state management with Proxy: a store without Redux

function createStore(initialState) {
  const listeners = new Set();
  const state = new Proxy(structuredClone(initialState), {
    set(target, key, value) {
      target[key] = value;
      listeners.forEach(fn => fn(structuredClone(target)));
      return true;
    }
  });
  return {
    state,
    subscribe: (fn) => { listeners.add(fn); return () => listeners.delete(fn); },
    getSnapshot: () => structuredClone(state),
  };
}
const cartStore = createStore({ items: [], total: 0 });
cartStore.subscribe(state => {
  document.getElementById('cart-count').textContent = state.items.length;
});

Project structure with ESModules

src/
  components/
    product-card.js
    modal.js
  lib/
    store.js
    api.js
    utils.js
  pages/
    catalog.js
    product.js
  app.js

{
  "type": "module",
  "scripts": {
    "dev": "vite",
    "build": "vite build"
  },
  "devDependencies": {
    "vite": "^5.0.0"
  }
}

Zero runtime dependencies. Vite is used only for development and building.

How We Work on Vanilla JS Projects

1. Analytics — identify critical scenarios, measure metrics (LCP, TTFB).
2. Design — module architecture, component map, API contracts.
3. Implementation — iterative development with code reviews and tests (Vitest + jsdom).
4. Optimization — bundle splitting, prefetch, lazy loading, tree-shake.
5. Deployment — build with Vite, deploy to CDN or hosting.

What is included in the work

• Source code in ESModules with comments.
• Component documentation and deployment instructions.
• 3-month support guarantee after delivery.
• Performance metrics before and after.

Estimated timelines

• Simple widget (up to 5 components) — from 2 to 5 days.
• Medium project (up to 20 components) — from 1 to 3 weeks.
• Complex application (up to 50 components) — from 4 to 8 weeks.

Pricing is determined individually. We will assess your project for free — write to us. Discuss your project — book a consultation. Additional budget savings of up to 50,000 RUB are possible when migrating from frameworks.

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

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

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.