TypeScript Interview Questions And Answers

Typescript interview questions are interviewers’ favorite questions which are generally asked in web development interviews. Typescript is a popular alternative Javascript programming language used in web development. This is a strongly compiled language working as a superscript of javascript with many additional features.

Typescript is used by many developers for their project and is hence one of the fastest adopting languages in the world of tech. In this blog, we will learn more about typescript programming language along with some of the basic typescript interview questions for freshers as well as professionals.

Table of Contents

What is Typescript Programming Language?

Typescript is the subset of javascript programming language with many added features like static typing, interfaces, and more. Typescript is a powerful combination used to make scalable and manageable applications.

Typescript interview questions and answers

Microsoft developed Typescript programming language and is also used and trusted by some of the global companies like Slack, Asana, Airbnb, Google, and more. This strongly typed programming language can provide better experience and hence is widely used in both frontend as well as backend programming.

20 Typescript Interview Questions and Answers For Beginners

Check some of the typescript interview questions and answers mentioned below especially for freshers.

What is TypeScript?

Ans: Typescript is a strong compiled programming language developed by renowned company Microsoft. It is a superset of Javascript programming language used in both frontend as well as backend type frameworks. It provides additional features such as static typing which means you can define variable types and avoid common bugs especially in large codebases.

How is TypeScript different from JavaScript?

Ans: Typescript is different from Javascript in terms of certain features such as it provides features like static types, interfaces, and better tooling support. It is compiled to plain JavaScript, so it can run anywhere JavaScript runs, but with more optimised structure and fewer errors.

Why should we use TypeScript?

Ans: This is a very common question asked in Typescript interview questions and answers and the answer is because it helps catch errors during development and thus help in improving code quality and making it easier to work in a team for a large project.

What is a Type in TypeScript?

Ans: A type in Javascript is something which tells what kind of values a variable can hold inside. For example, a number, string, boolean, or even a user-defined type like arrays, objects, and more. It avoids assigning any wrong values to the set of variables.

What is the difference between any and unknown types?

Ans: You can use an unknown type when you are not sure about the data but when you are aware then you use any type that you can assign or keep anything in it which can be safer or dangerous,does not matter. Hence it is important to do a type checking before you define one of the types.

What are interfaces in TypeScript?

Interfaces are used to define the shape of an object. It tells what properties an object should have and their types. This helps in writing cleaner and more predictable code, especially in large apps.

What are enums in TypeScript?

Ans: Enums in Typescript is a way to define a set of named constants. For example, you can define the directions like North, South, East, West using an enum, instead of using plain strings or numbers.

What is type inference in TypeScript?

Ans: Typescript is a mechanism which is used by the typescript compiler to automatically determine the type of a variable, return value, expression without the need for explicit type annotations.

Can you explain Union Types?

Ans: Union types allow variables to hold more than one type inside. It is a powerful way of declaring that a variable, parameter, and return value can be one of several specific data types.

What are literal types?

Ans: Literal types in typescript means a variable can hold only some specific value. For example, type Status = “success” or “error”. It helps restrict inputs to expected values only.

What is the difference between interface and type?

Ans: Interface and type both are used to define the object shape and can be extended while type is more flexible which can be used easily with unions, intersections, and more.

What are generics in TypeScript?

Ans: Generics in typescript are used to write reusable code that works with any type. For example, a function that works with both numbers and strings without losing type safety. It’s like writing one function for many data types.

How do you install TypeScript?

Ans: You can install TypeScript using npm by running npm install -g typescript. After that you can also use the tsc command to compile .ts files to JavaScript easily.

How do you compile a TypeScript file?

Ans: To compile a typescript file you have to use file extension i,e. .ts and run tsc filename.ts. It will generate a typescript file which can run in any browser or Node.js environment.

What is a tuple in TypeScript?

Ans: A tuple is a fixed-length array where each element can have a different type. For example, let person: [string, number] = [“John”, 25]. It helps in representing structured data like rows.

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What are optional properties in TypeScript?

Ans: Optional properties in typescript are those types which may or may not be present in an object. You can present them using the interrogative mark (?). For example, age?: number means the age property is not required.

What is never type in TypeScript?

Ans: The never type in Typescript is used for functions that never return. Variables can use type never when narrowed by any type which can never give true. For example, a function that throws an error or runs infinitely. It tells TypeScript that there’s no reachable return value.

How do you handle errors in TypeScript?

Ans: Typescript can be used to handle errors using the same try catch error handling as javascript. But with type support, you can handle specific error types and prevent unexpected bugs more easily. The error catch typescript interview questions are one of the most asked questions in an interview.

Can you extend interfaces in TypeScript?

Ans: Interfaces in typescript can extend other interfaces using the extend keyword easily. This help in reusing and combining multiple object structures into one simple clean interface.

What are the benefits of using TypeScript in frontend projects?

Ans: Typescript can be used in frontend projects easily to give a better code completion in IDEs. It improves collaboration among the developers and makes your app more stable and optimised over time.

5 Typescript Interview Questions and Answers For Professionals

Check some of the important Typescript interview questions and answers below.

What is the difference between interface and type in advanced use cases?

Ans: Interfaces in most cases are similar to type but type is considered to be more powerful while using Union, intersection, or mapping types. Interfaces are better for implementing classes. Type is more flexible in use cases like utility types, complex object combinations, and more. For example, you can’t use union types like type A = B | C with interfaces, but you can with type.

What are utility types in TypeScript?

Ans: Utility types are built in features in typescript which are used to transform or construct types. They usually make use of pick, partial, pick, record, etc. These utility types in typescript are used to save a lot of time and reduce manual typing when handling large object structures.

How does TypeScript support advanced function types?

Ans: Typescript is used to allow us to define major function types with input and output types using generics. You can also use default and optional parameters. But for advanced use you can define types for callbacks, higher order functions, and more.

What is TypeScript declaration merging?

Ans: Declaration in typescript is a unique feature which is used where the compiler merges two declarations with the same name into one. The declaration feature is used with interfaces and namespaces.

For example, if two interfaces with the same name are defined, TypeScript will merge their properties. It’s useful for extending third-party types or writing custom definitions.

How do generics improve code reusability in TypeScript?

Ans: Generics in typescript lets you write a function or class which works with different types without losing any type safety. We do not start writing separate versions for string, number, etc instead we use placeholder i,e. <T> and let the caller decide the type.

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Typescript Interview Questions and Answers FAQs

Q1. What is typescript language?

Ans: Typescript is the subset of javascript programming language with many added features like static typing, interfaces, and more. Typescript is a powerful combination used to make scalable and manageable applications.

Q2. Where can we find typescript interview questions and answers?

Ans: You can search for typescript interview questions and answers easily by searching on Google. We have covered important questions for freshers as well as professionals in typescript.

Q3. Does this blog contain typescript interview questions with answers?

Ans: Yes, in this blog, you will get a complete set of 25 typescript interview questions and answers especially for beginners as well as professionals.

Q4. Are interview questions enough for preparation?

Ans: If you are familiar with the frequent interview questions asked during the interviews then your preparation is much better than every other person who is neglecting this part.