Q01. What is TypeScript, and how does it relate to JavaScript?
TypeScript is a statically checked superset of JavaScript that adds a type system and compile-time tooling. It is typically transformed into JavaScript for execution. Its types are erased, so runtime validation must be implemented separately for untrusted values.
TypeScript source is checked and transformed; JavaScript runs in the runtime. Types improve static correctness but do not add automatic runtime validation.
Note
Interview approach: define the concept, explain why it matters, then mention one trade-off or limitation.
TypeScript compilation
const greeting: string = "Hello";
console.log(greeting);💡 The type annotation is removed from emitted JavaScript; the runtime executes the string value.
Key Takeaways
- Explain the concept in your own words.
- Know the practical trade-off and its limits.
- Use a small example to demonstrate the idea.
Knowledge Check
Which language normally executes in a browser after standard TypeScript compilation?