Migrating Ekehi from Vanilla JS to a TypeScript Stack

Ekehi platform has moved from hand-written HTML/CSS/JS pages to a typed, component-driven React 19 client and a module-based TypeScript Express/Node.js API. 0. Where we started and where we landed Before. A static client built from per-page folders ( landing/ , contributors/ , login/ , signup/ , admin/ ), each shipping its own index.html , a shared styles.css , and vanilla ES module scripts under client/shared/ . The server was an Express API written in plain JavaScript. After. Layer Before After Client Static HTML + CSS + vanilla JS React 19 + Vite 8 + TanStack Router + TypeScript 6 Styling One global styles.css Tailwind CSS 4 with @theme design tokens Data fetch scattered per page TanStack Query over a typed lib/api client Server Express in JavaScript Express + TypeScript, module-per-domain Repo Two loose folders pnpm workspace with shared git hooks Quality gate None ESLint 9, Prettier 3, Husky, commitlint, Vitest The migration ran in two phases on separate branches: **Phase 1 — client rewrite. **Phase 2 — server rewrite. 1. Why this framework? Choice: React 19 , rendered as a client-side SPA through Vite 8 , routed by TanStack Router . TanStack Router was chosen rather than React Router because it gives fully type-safe routes, first-class search-param typing, built-in code-splitting, and file-based route generation that pairs cleanly with Vite. 2. The folder and component structure The client uses a feature-sliced layout: code is grouped by domain, not by technical type. client/src/ ├── components/ │ ├── layout/ navbar.tsx, footer.tsx │ └── ui/ button, input, modal, select, dropdown, ... (design system) ├── config/ env.ts, env-schema.ts, endpoints.ts ├── features/ one folder per domain │ ├── auth/ auth.query.ts, auth.service.ts, auth.types.ts, components/, pages/ │ ├── opportunities/ pages/ │ ├── resources/ pages/ │ ├── submissions/ pages/ │ ├── admin/ pages/ │ └── site/ pages/ (landing, contributors) ├── lib/ │ ├── api/ request.ts, errors.ts, refresh.ts, types.t