CityJS London 2025
as the organisers put it
Join us from April 15–17, 2026, at Kensington Town Hall for CityJS London. Experience 3 days of workshops, meetups, and a full-day conference with 30+ speakers covering JavaScript, TypeScript, AI, Svelte, and more.
| title | author | length |
|---|---|---|
| Await for it | Rich Harris | 19m |
Spelt implements a compiler-driven await-in-components model that hoists pure async expressions, runs them in parallel, and coordinates updates so the UI… | ||
| Hacking AI Applications | Liran Tal | 31m |
Generative-AI code and integrations produce concrete vulnerabilities: a February 2025 study of ~733 snippets finds ~25% of JavaScript lines vulnerable and only… | ||
| The Untold History Behind Lynx | Zack Jackson | 20m |
Rspack originates as a custom bundler built because existing tools couldn’t handle Lynx’s native constraints: a 90‑day Spring Festival app with hundreds of… | ||
| Effect: Production-Grade TypeScript | Michael Arnaldi | 27m |
Effect is a TypeScript runtime and library that models side effects as lazy, composable values, offering interruptible by default execution, retries with… | ||
| Building an in-browser code editor (that can run your code too!) | Jo Franchetti | 21m |
Builds a React + TypeScript editor that actually executes user code by sending the typed source to Dino subhosting serverless functions and returning a unique… | ||
| Full Stack Web Development with AI | Tamas Piros | 24m |
Condensed demo builds a streaming chatbot with Next.js and the Vercel AI SDK, wiring a POST API route to stream tokens to a front-end useCompletion/useChat… | ||
| From the crypt to the code: Web security explored through horror movies | Ramona Schwering | 24m |
Maps OWASP Top 10 failures to horror beats and gives concrete defenses: Broken access control — deny by default, minimal privilege, short JWTs + refresh tokens… | ||
| The Upside of Being Unreasonable | Jason Lengstorf | 29m |
Argues that the old devrel playbook is dead and shows how a slow hunch becomes a business: requests $500,000 from leadership, quits a tech executive role end… | ||
| From Fragile to Future-Proof: Solving Web Monetization Chaos... | Faris Aziz | 23m |
Front-end implements a rules-driven payment orchestration layer that chooses gateways by country, currency and AB test segment, orders an array of providers… | ||
| Pay the Web Forward | Peter-Paul Koch | 23m |
Proposal to shift web funding from ads to voluntary microstreams using Web Monetization: a browser extension sets a suggested rate 60, the visitor’s wallet… | ||
| Event Driven Frontends. What, why and how. | Matthew Cox | 20m |
Brings raw business events into the browser, fetches per-customer daily event logs plus snapshots, loads them into a WASM SQLite stored in OPFS, and runs SQL… | ||
| Bill and Ted’s accessibility adventure: Accessibility testing for developers | Alistair Shepherd | 22m |
Argues that teaching developers accessibility through hands‑on accessibility testing works better than reading or lectures, and demonstrates concrete tools and… | ||
| The news of the death of JavaScript has been greatly exaggerated | Vladimir de Turckheim | 19m |
Gives a 1995–2025 timeline showing concrete attempts to replace JavaScript: browser forks like JScript/VBScript, plugin ecosystems (Flash and Java applets that… | ||
| Speed at Scale: Optimizing The Largest CX Platform Out There | Matheus Albuquerque | 17m |
Platform serves 15mi+ sessions/month and migrates a huge legacy React codebase using automated transforms, staged generations behind feature flags, and code… | ||
| 3D graphics in React & React Native using React-three-fiber | Perttu Lähteenlahti | 27m |
Shows that a single JSX codebase using react-three-fiber plus Expo and Three.js runs the same 3D scenes on web, iOS and Android (example repo and Play/App… | ||
| Generative AI for Front-end Developers | Adam Cowley | 19m |
Shows how to build a retrieval augmented front end using LangChain, with concrete code: prompt templates, chat placeholders, and a runnable that formats… | ||
| At the top of the pyramid: Playwright testing at scale | Kate Marshalkina | 18m |
Project grows from zero to 20,000 lines of Playwright tests in a year, using Playwright features like the trace viewer, AI-assisted prompts, and a step… | ||
| High-quality, performant images & videos on your React website (and some AI magic!) | Rahul Nanwani | 14m |
Starts from a 64 Lighthouse score and shows concrete steps to reach about 94 by swapping plain img/video tags for the ImageKit SDK components, enabling… | ||
| Architecting Multi-Tenant Solutions with Next.js and the App Router | Guilherme Dalla Rosa | 22m |
A production Next.js multi-tenant storefront runs for two years using the App Router, middleware that does a middleware lookup table from incoming… | ||
| nothing matches | ||