What are the main differences between TypeScript and JavaScript?
Why Interviewers Ask This
This is a classic screening question for TypeScript roles. Hiring managers ask it early in interviews to gauge your baseline understanding and determine if you can communicate technical concepts clearly.
Answer
TypeScript vs JavaScript key differences: (1) Static Typing — TypeScript has optional static types; JavaScript is dynamically typed. Types in TS are checked at compile time, preventing type-related bugs before they reach production. (2) Compilation — TypeScript must be compiled to JavaScript before it can run; JavaScript runs directly in the browser/Node. (3) Type Annotations — TS allows you to annotate variables, function parameters, and return types explicitly. (4) Advanced OOP features — TS adds interfaces, access modifiers (public/private/protected), abstract classes, and decorators. (5) Better IDE support — TypeScript enables richer autocomplete, refactoring, and error detection in editors. (6) Backwards compatibility — TypeScript can target any JavaScript version (ES5, ES6, ESNext). All JavaScript code is valid TypeScript, making migration incremental.
Pro Tip
Before answering, structure your response: one-line definition → real-world analogy → concrete example from a project. This makes even complex TypeScript answers easy to follow.