Types at the edges of your system

Find and fix your TypeScript blind spots

😃 Coding with TypeScript feels safe, the compiler has your back.

😨 But today, you got a critical issue in prod: payments are failing! A quick check of the logs left you puzzled: TypeError: discount.toFixed is not a function.

😕 Wait… Isn't discount supposed to be a number here? How did that happen? Why didn't TS catch it before?! Worry no more.

🤠 In this talk, I will show you where your blind spots are, and a simple way for you to fix them.

Mazda head units got bricked by a local NPR station in Seattle in February 2022. Better validation at the edges would have save them a lot of trouble (and money).

🧰 Resources

Slides of my talk
Why array[0] doesn't return T | undefined by default?
Parse, Don't Validate
Advanced TypeScript Patterns: API Contracts
Fixing TypeScript's Blindspots: Runtime Typechecking
colinhacks/zod the TypeScript-first schema validation with static type inference

Written by Nicolas Carlo who lives and works in Montreal, Canada 🍁
He founded the Software Crafters Montreal community which cares about building maintainable softwares.