Modern Front-End Development for Rails, 2nd Edition

Using TypeScript

We’ve already installed TypeScript back in ​Adding TypeScript​ by using the tsc_watch tool to run TypeScript’s type checker over our code base, and then using esbuild to convert our TypeScript code into JavaScript. TypeScript’s configuration is managed by a tsconfig.json file, which basically specifies what TypeScript allows and the kind of code that TypeScript emits. (I’ll talk about more about the tsconfig.json file in Chapter 13, ​Validating Code with Advanced TypeScript​.)

With TypeScript in place and with tsc_watch, every time we make a file change the TypeScript type checker will run, and if all its type checking passes, esbuild will convert it to JavaScript that can be sent to the browser. If the type checking does not ...