Quiz Application

A quiz application presents questions, accepts answers, computes a score, and explains mistakes. Keeping answer evaluation separate from display allows the same quiz to work in a CLI, browser, or test runner.

The evaluator normalizes case and trims user responses. Both answers match, so it reports 2/2. A UI would present explanations and track progress separately.

Comparing the answer array and question array without handling missing positions can accept or display incorrect results.

This source was compiled using TypeScript 5.8.3 with strict checking, then executed with Node.js 22.16.0. Its stdout below is the actual captured output. The core logic is runnable without a framework or a remote API; integration-specific examples appear in a separate lab when needed.

TypeScript source

type Question = { prompt: string; answer: string; explanation: string };
function evaluate(questions: readonly Question[], answers: readonly string[]): number {
  return questions.reduce((score, question, index) => score +
    (question.answer.toLowerCase() === (answers[index] ?? "").trim().toLowerCase() ? 1 : 0), 0);
}
const quiz: Question[] = [
  { prompt: "Which keyword declares a constant?", answer: "const", explanation: "const prevents reassignment." },
  { prompt: "What does tsc emit?", answer: "javascript", explanation: "tsc emits JavaScript when emission is enabled." },
];
console.log(`Score: ${evaluate(quiz, ["CONST", "JavaScript"])}/${quiz.length}`);

Verified output

Score: 2/2

Compile: npx tsc --strict --target es2022 --module commonjs quiz-application.ts; run: node quiz-application.js. For examples importing node: modules, install @types/node as a development dependency; for browser or React projects use the separate lab setup.

The evaluator normalizes case and trims user responses. Both answers match, so it reports 2/2. A UI would present explanations and track progress separately.

Before editing the code, predict what the output will be for one changed input. Run it and compare your prediction with the actual result.

Comparing the answer array and question array without handling missing positions can accept or display incorrect results.

Determine whether the issue belongs to the type system, a trust boundary, or actual runtime behavior before choosing a correction.

Add multiple-choice options and a timed mode. Test blank answers and questions whose case matters.

Record expected success and failure outcomes, run the code, and compare the observed behavior. Keep the exercise compatible with strict type checking.

The evaluator normalizes case and trims user responses. Both answers match, so it reports 2/2. A UI would present explanations and track progress separately.

Apply the same reasoning to the practice task, then integrate it into a real app only when the runtime and dependency setup are ready.