Windsurf Case Study: Solo Developer Migrates Legacy jQuery E-Commerce Site to Next.js in 5 Days
From jQuery Spaghetti to Next.js in Five Days: A Solo Developer’s Windsurf Migration Story
When freelance developer Marcus Chen landed a contract to modernize a six-year-old jQuery e-commerce platform with 80+ components, 14,000 lines of JavaScript, and zero TypeScript coverage, the client expected a three-week timeline. Using Windsurf’s AI-powered IDE, he delivered in five days. This case study breaks down exactly how.
The Legacy Codebase: What We Started With
- Framework: jQuery 3.3.1 with Handlebars templates- Components: 83 loosely coupled UI modules- Lines of code: ~14,200 JS, ~6,800 HTML/CSS- Build system: Gulp with manual concatenation- Pain points: No type safety, global state mutations, inline event handlers, mixed concerns
Why Windsurf Was the Right Tool
Unlike traditional AI code assistants that operate on single files, Windsurf’s Cascade mode understands entire codebases. For a migration this size, three capabilities proved essential:
- Codebase-wide understanding — Windsurf indexed all 83 components and mapped their dependency graph before suggesting any changes.- Multi-file refactoring flows — A single prompt could refactor a jQuery plugin into a React component, update all imports, and adjust parent components simultaneously.- Cascade auto-resolution — After the initial conversion, 217 TypeScript errors appeared. Cascade resolved 203 of them automatically in a single pass.
Day-by-Day Migration Workflow
Day 1: Setup and Codebase Indexing
Install Windsurf and initialize the project:
# Install Windsurf IDE (macOS/Linux)
curl -fsSL https://windsurf.com/install.sh | sh
Or download from windsurf.com for Windows
Launch and open your project directory
windsurf ~/projects/legacy-ecommerce
Initialize Next.js alongside the legacy code
npx create-next-app@latest next-ecommerce —typescript —tailwind —app
cd next-ecommerce
npm install
Open Windsurf’s Cascade panel (Cmd+Shift+P → “Cascade: Open”) and let it index the legacy codebase:
# In Cascade prompt:
Analyze the ../legacy-ecommerce directory. Map all jQuery components,
their dependencies, shared utilities, and global state patterns.
Create a migration plan prioritized by dependency depth.
Windsurf produced a dependency graph and a suggested migration order — leaf components first, layout shells last.
Day 2: Core Component Conversion
Using multi-file refactoring, Marcus converted the product catalog module — the largest single piece at 1,400 lines:
# Cascade prompt:
Convert legacy-ecommerce/src/js/product-catalog.js and its
Handlebars template product-catalog.hbs into a Next.js App Router
page at app/products/page.tsx. Replace jQuery AJAX calls with
Server Actions. Preserve all filtering logic. Use TypeScript strict mode.
Windsurf generated five files in one pass:
app/products/page.tsx — Server Component with data fetching
app/products/ProductGrid.tsx — Client Component for interactive grid
lib/types/product.ts — TypeScript interfaces
lib/actions/products.ts — Server Actions replacing $.ajax
app/products/loading.tsx — Streaming skeleton UI
Here is the converted Server Action replacing the original jQuery AJAX call:
// lib/actions/products.ts
‘use server’
import { Product, FilterParams } from ’@/lib/types/product’
export async function fetchProducts(filters: FilterParams): Promise<Product[]> {
const params = new URLSearchParams()
if (filters.category) params.set(‘category’, filters.category)
if (filters.minPrice) params.set(‘min_price’, String(filters.minPrice))
if (filters.maxPrice) params.set(‘max_price’, String(filters.maxPrice))
params.set(‘page’, String(filters.page || 1))
params.set(‘limit’, String(filters.limit || 24))
const res = await fetch(
${process.env.API_BASE_URL}/products?${params},
{
headers: { ‘Authorization’: Bearer ${process.env.API_KEY} },
next: { revalidate: 60 }
}
)
if (!res.ok) throw new Error(‘Failed to fetch products’)
return res.json()
}
The corresponding ProductGrid client component:
// app/products/ProductGrid.tsx
‘use client’
import { useState, useTransition } from ‘react’
import { fetchProducts } from ’@/lib/actions/products’
import type { Product, FilterParams } from ’@/lib/types/product’
export default function ProductGrid({ initial }: { initial: Product[] }) {
const [products, setProducts] = useState(initial)
const [isPending, startTransition] = useTransition()
function handleFilter(filters: FilterParams) {
startTransition(async () => {
const results = await fetchProducts(filters)
setProducts(results)
})
}
return (
{isPending && Loading...}
{products.map((p) => (
{p.name}
${p.price.toFixed(2)}
))}
)
}
Day 3: Batch Conversion of Remaining Components
Marcus grouped the remaining 78 components into batches by feature area and ran Cascade prompts for each group:
# Cascade prompt (batch mode):
Convert these 12 cart-related jQuery modules to React components:
cart-drawer.js, cart-item.js, cart-summary.js, cart-upsell.js, cart-discount.js, mini-cart.js, cart-shipping.js, cart-tax.js, cart-empty.js, cart-counter.js, cart-note.js, cart-gift.js Use Zustand for cart state instead of window.cartState global. Place output in components/cart/ with proper TypeScript types.
Day 4: TypeScript Error Resolution with Cascade
After converting all components, running npx tsc --noEmit revealed 217 TypeScript errors. Marcus triggered Cascade auto-resolution:
# Cascade prompt:
Run TypeScript compiler and fix all errors across the codebase.
Prefer strict typing over 'any'. Add missing interface properties.
Fix event handler types for React synthetic events.
Resolve module resolution issues.
Results after a single Cascade pass:
| Metric | Before Cascade | After Cascade |
|---|---|---|
| Total TS errors | 217 | 14 |
| Auto-resolved | — | 203 (93.5%) |
| Manual fixes needed | — | 14 |
| Files modified | — | 64 |
| Time elapsed | — | ~8 minutes |
Day 5: Testing, Optimization, and Deployment
# Generate test stubs with Windsurf
Cascade prompt:
Generate Jest + React Testing Library tests for all components
in components/cart/. Cover add-to-cart, remove, quantity update,
and discount application flows.
Run the full suite
npm run test — —coverage
Build and deploy
npm run build
vercel deploy —prod
Pro Tips for Power Users
- Use Cascade context pinning: Pin critical files like your type definitions and API client so every Cascade prompt has consistent context without re-specifying them.- Batch by dependency layer: Convert leaf components first, then work upward. This prevents cascading breakage during migration.- Set .windsurfrules: Create a
.windsurfrulesfile in your project root with project conventions so Cascade output stays consistent:
- Incremental verification: After each batch conversion, run# .windsurfrules framework: next.js 14 app router style: tailwind css state: zustand for client state, server actions for mutations types: strict typescript, no ‘any’ components: functional only, named exports testing: jest + react testing librarynpx tsc —noEmitbefore moving on. Catching errors early keeps Cascade resolution efficient.- Leverage Cascade memory: Windsurf remembers prior refactoring decisions within a session. Early corrections propagate automatically to later conversions.
Troubleshooting Common Issues
| Error | Cause | Solution |
|---|---|---|
Cannot find module '@/lib/types' | tsconfig paths not configured | Ensure tsconfig.json includes "paths": {"@/*": ["./src/*"]} matching your project structure |
Cascade suggests any types | Insufficient context about data shapes | Pin your API response type files before running conversion prompts |
| Event handler type mismatches | jQuery events vs React SyntheticEvent | Prompt Cascade specifically: "Use React.MouseEvent and React.ChangeEvent, not DOM Event types" |
| Hydration mismatch errors | Server/client rendering differences | Add 'use client' directive to components using browser APIs or state. Use dynamic(() => import(...), { ssr: false }) for jQuery widget wrappers during incremental migration |
| Cascade modifies unrelated files | Over-broad prompt scope | Be specific about which files to modify. Use file path references in prompts rather than general descriptions |
| Metric | Before (jQuery) | After (Next.js) |
|---|---|---|
| Lighthouse Performance | 38 | 94 |
| First Contentful Paint | 4.2s | 0.8s |
| Bundle size (gzipped) | 412 KB | 127 KB |
| Type safety coverage | 0% | 98.4% |
| Development time | Est. 15-20 days manual | 5 days with Windsurf |
Can Windsurf handle migrations from frameworks other than jQuery?
Yes. Windsurf's codebase understanding works with any JavaScript or TypeScript project. Developers have documented successful migrations from AngularJS, Backbone.js, Ember, and vanilla JavaScript to modern frameworks like Next.js, Nuxt, and SvelteKit. The key is providing clear Cascade prompts that specify the source and target patterns.
How does Windsurf’s Cascade mode differ from using ChatGPT or Copilot for large refactors?
Cascade maintains awareness of your entire project simultaneously. While single-file AI assistants require you to manually copy context between files, Cascade tracks cross-file dependencies, shared types, import chains, and state management patterns. This is why it could resolve 203 TypeScript errors in one pass — it understood how changes in one file would ripple across 64 others.
Is Windsurf suitable for team projects or only solo developers?
Windsurf works for teams of any size. The .windsurfrules configuration file can be committed to version control so all team members get consistent AI behavior. For larger teams, Cascade’s multi-file awareness becomes even more valuable since it respects existing code conventions across a broader contributor base. The solo developer scenario in this case study simply highlights the productivity multiplier effect most dramatically.