#type safety

The Talk discusses the limitations of TypeScript and the lies we tell ourselves about its type safety. It explores examples of unsafe operations and bending the type system using keywords like type assertion and function is dice. The Talk also covers catching syntax errors, type mismatches, and the complexity of conditional types and generics. It emphasizes the importance of understanding TypeScript's limitations and making well-informed decisions as software engineers.

Hi, everyone. Today, I'll be showing you some of the features that modern frameworks implement or frameworks that leverage Typescript implement to improve the developer and user experience. I'll cover some of the features that Expo with Expo Router and Next.js with the AppRouter implements. Let's talk about setting up TypeScript in both Expo and Next.js. Both frameworks provide a TypeScript-first development experience. The most important feature is type safe routing, which enhances developer productivity and app stability. Frameworks provide a built-in link component for link generation. It reduces the risk of typos and throws type errors when linking to non-existent routes. In Expo, enable the .typed experiment and import the link component from the exporouter package. Expo supports static and dynamic routes, and throws errors for incorrect parameters. ExpoRouter provides hooks like UseSegments and UseRouter for more control. In Next.js, enable typedRoutes in the next config file. We can import the link component from the next link package and restart the dev server after updating the next config file. Next.js automatically generates route definitions and includes the type file in the TS config. Autocompletion is available for the href attribute, which can be a string or dynamic value. Next.js provides hooks like use router for static navigation and router.push to prevent redirection to broken routes. Catch all routes in type safe routing pose a challenge for enforcing type safety on the href attribute. TypeScript may not throw an error for routes that may be broken or lead to unwanted pages. Keep this in mind when working with catch all routes. Before a production build, route types should be in place to ensure accurate type definitions. Generating routes is an ongoing task that needs to happen at the right moment to avoid build-time errors. When implemented correctly, type-safe routes can elevate the developer experience by preventing broken links or dysfunctional routes. In Next.js, server components and client components have different limitations. Next.js provides automatic error checking for importing useState in server components and enforces the useClientDirective to prevent using client-related code in the wrong places. Next.js also ensures type safety by throwing errors for invalid segment config options and requiring the alt attribute for image components to improve accessibility. Config files in Expo and Next.js have different approaches to incorporating TypeScript, with Expo using the TS node require hook and Next.js supporting type checking through jsdoc in the config JS file. By enabling type-safe routing, we catch potential issues at compile time, ensuring robust routes and unbroken links. Many other frameworks and tools leverage TypeScript to empower developers and deliver error-free experiences to users.