Top 10 TypeScript Interview Questions with Answers

By Nitin Pandit | Views: 936

Here are some commonly asked TypeScript interview questions and their answers:

Q1. What is TypeScript, and what are its advantages?

Answer: TypeScript is a superset of JavaScript that provides optional static typing, enhanced syntax, and better tooling support. Its main advantages include improved code maintainability, better code navigation, and fewer runtime errors.

Q2. How does TypeScript help in catching errors?

Answer: TypeScript provides static type checking, which helps in catching errors during compile-time rather than runtime. This ensures that the code is more robust and fewer bugs are present during the development stage.

Q3. What is the difference between "any" and "unknown" types in TypeScript?

Answer: The "any" type can represent any value and allows the code to bypass TypeScript's type checking. On the other hand, the "unknown" type is like "any," but it requires type checking before performing any operation with it. This makes the code safer and more maintainable.

Q4. What is the difference between "interface" and "class" in TypeScript?

Answer: An interface is a blueprint for an object's structure and defines the properties and methods that an object must have. On the other hand, a class is a blueprint for creating objects, and it defines the properties and methods of an object as well as its behaviour.

Q5. What are decorators in TypeScript?

Answer: Decorators are a feature of TypeScript that allows adding metadata to a class declaration, method, accessor, property, or parameter at design time. This metadata can then be used by other code to determine how to interact with the decorated item.

Q6. How can you declare a variable as optional in TypeScript?

Answer: You can declare a variable as optional in TypeScript by using the "?" symbol after the variable name. For example, "let age?: number;" would declare the age variable as optional.

Q7. What is the use of generics in TypeScript?

Answer: Generics in TypeScript allow creating functions, classes, and interfaces that can work with multiple types of data. This enables the creation of more flexible and reusable code.

Q8. What is a namespace in TypeScript?

Answer: A namespace is a way of organizing code in TypeScript, and it is used to group related code into a single namespace. This prevents naming conflicts and makes the code easier to manage.

Q9. What is a module in TypeScript?

Answer: A module is a way of organizing code in TypeScript, and it is used to group related code into a single unit. Modules can be exported and imported by other code, making it easier to reuse code across different files.

Q10. What is the difference between "readonly" and "const" in TypeScript?

Answer: The "readonly" keyword can be used to make a property or variable read-only after it is initialized. The "const" keyword, on the other hand, is used to declare a constant that cannot be reassigned once it is initialized.

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