Decorators & Project Setup — Series 3

Preview — 3 of 10 questions

javascript

// noImplicitOverride: true
class Base {
  greet(): string { return "hi"; }
}

class Child extends Base {
  greet(): string { return "yo"; }
}

ACompiles fine — the flag only warns when override is used on a member the base does not have

BCompiles fine — noImplicitOverride applies to properties, not methods

CCompile-time error — with the flag on, a member that overrides a base member must be marked override

DCompile-time error — Child may not narrow the return type of greet

javascript

// package.json
{ "type": "module" }

// tsconfig.json
{ "compilerOptions": { "module": "node16", "moduleResolution": "node16" } }

AA compile-time error — under node16, an ESM file must use a fully specified relative path including the .js extension

BCompiles fine — TypeScript always resolves extensionless relative imports

CCompiles fine, but the emitted JavaScript rewrites the path to ./helper.js

DA compile-time error — module: "node16" may not be combined with "type": "module"

What does the emitted JavaScript import?

javascript

import type { User } from "./models";
import { logger } from "./logger";

export function greet(u: User): void {
  logger.info(u.name);
}

ABoth ./models and ./logger

BNeither — TypeScript removes all imports it can prove are unused at runtime

COnly ./models

DOnly ./logger — an import type statement is erased entirely, so ./models is never even loaded at runtime

Answer all 10 questions (7 more), see explanations for every answer, and track your score.