interface WeatherReport temp: number; humidity: number; city: string;
When you use if (isAddAction(action)) , TypeScript narrows the type inside the block. Grider calls this "teaching the compiler your business logic."
After his course, you will open a tsconfig.json and see not a wall of noise, but a safety checklist. You will write functions where the type signature tells a story: "Given this, I guarantee that." You will refactor a 500-line JavaScript file into a 200-line TypeScript file, removing entire categories of bugs.
interface WeatherReport temp: number; humidity: number; city: string;
When you use if (isAddAction(action)) , TypeScript narrows the type inside the block. Grider calls this "teaching the compiler your business logic." typescript stephen grider
After his course, you will open a tsconfig.json and see not a wall of noise, but a safety checklist. You will write functions where the type signature tells a story: "Given this, I guarantee that." You will refactor a 500-line JavaScript file into a 200-line TypeScript file, removing entire categories of bugs. interface WeatherReport temp: number