- TypeScript – Interview Questions
The questions a TypeScript role actually asks, answered against the twenty lessons before this one. any versus unknown, interface versus type, why enum is contentious, what structural typing means in practice, how narrowing works, what erases at build time and what does not. Short answers, with the reasoning behind them.
- NestJS – Interview Questions
The questions that actually get asked, with answers drawn from the nineteen lessons before this one — module scope and why a provider is not global, guards versus middleware versus interceptors, how Nest resolves a dependency, why the global ValidationPipe matters, and what happens to an exception on its way out.
- TypeScript – With React
Typing props and children, useState where inference is enough and where it is not, useRef's two different types, event handlers, and generic components. Plus the context pattern that removes the `| undefined` every consumer would otherwise have to handle, taken from this app's auth provider.
- NestJS – Testing
Test.createTestingModule, mocking a provider with useValue, and getting the token right — @InjectDataSource does not ask for the class, so overriding the class leaves your test talking to the real database. Then e2e with supertest, and the trap that makes a whole suite pass vacuously: forgetting the global pipe.
- TypeScript – Decorators
A decorator is a function that runs when the class is defined. What @Injectable, @Column and @Post are really doing, the metadata reflection that lets a framework read your parameter types at runtime, writing your own, and the split between the legacy experimentalDecorators and the standard ones — with which this app uses.