Top TypeScript Interview Questions and Answers TypeScript, a statically typed superset of JavaScript, has become increasingly popular among developers for its ability to catch errors early and enhance code maintainability. If you're preparing for a TypeScript interview, it's essential to be familiar with the most commonly asked questions. This article outlines some of the top TypeScript interview questions along with their answers. Basic TypeScript Questions 1. What is TypeScript? Answer: TypeScript is a statically typed superset of JavaScript developed by Microsoft. It compiles to plain JavaScript and adds features like static typing, classes, and interfaces, which help in writing robust and maintainable code. 2. How do you install TypeScript? Answer: TypeScript can be installed using npm (Node Package Manager) with the following command: bash Copy code npm install -g typescript 3. What are the advantages of using TypeScript? Answer: The main advantages include: Static Typing: Helps catch errors at compile time rather than at runtime. Improved IDE Support: Offers better code completion, refactoring, and documentation. Object-Oriented Features: Supports features like classes, interfaces, and inheritance. Compatibility: Compiles to JavaScript, ensuring compatibility with all browsers. Intermediate TypeScript Questions 4. What are TypeScript types? Answer: TypeScript types include basic types like number, string, boolean, as well as complex types like arrays, tuples, enums, any, void, null, undefined, and custom types using interfaces and type aliases. 5. What is the difference between interface and type in TypeScript? Answer: Both interface and type can be used to define the shape of an object. However, interface is more extendable and can be used to declare an interface that can be implemented by a class or extended by other interfaces. type is more flexible and can define union types, intersection types, and other complex types. 6. Explain the concept of Union and Intersection types in TypeScript. Answer: Union Types: Allow a variable to be one of several types. Use the | operator. typescript Copy code let value: string | number; Intersection Types: Combine multiple types into one. Use the & operator. typescript Copy code type Employee = { name: string; } & { age: number; }; 7. How do you define a class in TypeScript? Answer: A class in TypeScript is defined using the class keyword. It can include properties, constructors, and methods. typescript Copy code class Person { name: string; constructor(name: string) { this.name = name; } greet() { console.log(`Hello, my name is ${this.name}`); } } Advanced TypeScript Questions 8. What are generics in TypeScript? Answer: Generics allow you to create reusable components that work with various types instead of a single one. This ensures type safety and reusability. typescript Copy code function identity<T>(arg: T): T { return arg; } 9. What is the never type in TypeScript? Answer: The never type represents values that never occur. It is used for functions that never return or always throw an error. typescript Copy code function error(message: string): never { throw new Error(message); } 10. Explain type assertion in TypeScript. Answer: Type assertion allows you to override the inferred type of a variable. It can be done using the as keyword or angle-bracket syntax. typescript Copy code let someValue: any = "Hello World"; let strLength: number = (someValue as string).length; 11. What are decorators in TypeScript? Answer: Decorators are special declarations that can be attached to a class, method, accessor, property, or parameter. They enable additional functionality and are used extensively in frameworks like Angular. typescript Copy code function readonly(target: any, key: string) { Object.defineProperty(target, key, { writable: false, }); } class Person { @readonly name: string; } source : Typescript Interview Questions https://resumeforrest.com/blog/typescript-interview-questions-advanced