Testing types in TypeScript is crucial for SDK and API developers to ensure predictable type inferences. Tools like `tsc`, `dtslint`, `tsd`, and `Vitest` can help catch errors early and guarantee type behavior.
Node.js introduces `--experimental-strip-types` flag to run TypeScript files directly without transpiling, speeding up development. This sounds great but it currently leads to compatibility issues and lack of TypeScript features. The community is discussing concerns and potential solutions for the future.
TypeScript has two concepts: type annotations and type inference. Type annotations involve explicitly specifying the type of a parameter or variable, while type inference occurs when TypeScript automatically determines the type based on the implementation.
TypeScript has a structural type system, which means that types are compatible based on their shape or structure rather than their names. This allows you to interchangeably use types with different names but identical properties. You can assign one type to another if they share the same properties, including optional properties.
Branded types in TypeScript can help catch programming errors early by ensuring that values meet certain criteria before they are used. To create a branded type, you add a readonly property to an existing type. Branded types are especially useful when combined with assertion functions, which validate inputs and assert the branded type after successful validation.