Top 25 TypeScript Interview Questions and Answers in 2022


TypeScript Interview Questions and Answers

Interviews are a key part of finding out what type of job candidate you want to hire, and the best way to prepare for them is to practice with mock interviews. TypeScript is a programming language that has been growing in popularity as it allows developers to program using object-oriented coding principles. I am a web developer and I have been asked in an interview to write a piece of code in TypeScript.  In this article, I’ll share my own experience of preparing for a TypeScript interview, as well as some tips on what to expect.

1. What Is Typescript?

TypeScript is a programming language that allows developers to write code in a more organized and structured way. It is a superset of JavaScript, meaning that all JavaScript code is valid TypeScript code. However, TypeScript adds additional features that make it more powerful and efficient. For example, TypeScript supports type annotations, which allows developers to specify the data type of a variable. This can help to prevent errors, and also makes code more readable. TypeScript is also compiled, meaning that it is converted into JavaScript code before it is run. This allows for faster and more efficient execution.

2. What Are The Typescript Tools?

I’ve been using TypeScript for a while now and I absolutely love it! The tools make my life so much easier and I highly recommend them to anyone who is looking for a better way to write JavaScript.

Here are some of the TypeScript tools that I use:

●     The TypeScript Compiler

Why Should We Hire You? 5 Best Answ...
Why Should We Hire You? 5 Best Answers

This tool allows you to compile your TypeScript code into JavaScript. It’s really easy to use and it makes your code a lot more readable.

  • The TypeScript Language Service

This tool provides you with auto-complete and types checking for your TypeScript code. It’s really helpful and it can save you a lot of time.

  •   The TypeScript Definition Manager

This tool allows you to manage your TypeScript definitions. It’s really easy to use and it can help you keep your project organized.

3. What Are The Benefits Of Using Typescript?

I’ve found that using TypeScript has a few benefits; here are my personal top three benefits:

  •  TypeScript Makes Code More Readable and Easier to Understand

TypeScript’s static type system and type annotations help to make code more self-documenting. This is especially useful when working on large projects with many developers, as it can help to prevent merge conflicts and make code reviews go more smoothly.

  • TypeScript Can Help to Prevent Bugs

The type system can catch many potential bugs at compile time before they have a chance to cause problems in production. This can save a lot of time and frustration in the long run.

  • TypeScript Is Easy to Learn

If you’re already familiar with JavaScript, learning TypeScript is a breeze. The syntax is very similar, so there’s not much to learn there. And, as I mentioned before, the type system can help to make code more self-documenting, which makes it easier to understand what’s going on.

4. What Is A Class In Typescript?

When I was preparing for my TypeScript interview, I knew that classes would be a topic of discussion. In TypeScript, a class is a blueprint for an object. It is a template that defines the variables and methods common to all objects of a certain type. Classes are typically used to represent real-world objects.

5. What Is The Difference Between Javascript And Typescript?

The main difference between JavaScript and TypeScript is that TypeScript is a typed superset of JavaScript, while JavaScript is an untyped language. This means that TypeScript adds extra features to JavaScript, such as type annotations and interfaces.

6. What Are Some Of The Features Of Typescript?

The features that stand out the most to me are its static type-checking, its support for ES6 features, and its ability to type-check React components props.

TypeScript’s static type-checking is a huge help when it comes to catching errors in my code. I can quickly find out if I’m using the wrong variable type or if I’m passing the wrong type of data to a function. This saves me a lot of time and prevents me from having to debug my code.

TypeScript’s support for ES6 features is also really useful. I can use all the latest features of JavaScript, such as arrow functions and template literals, without having to worry about compatibility issues. This makes my code more concise and easier to read.

Finally, TypeScript’s ability to type-check React component props is extremely helpful. It ensures that I’m passing the correct type of data to my components, which can prevent errors from happening down the road.

7. What Is The Difference Between A Function And A Method?

A function is a block of code that can be invoked from anywhere in your code, while a method is a function that is associated with an object.

8. What Is The Difference Between Var, Let, And Const?

Var is a keyword that is used to declare variables, let is a keyword that is used to declare variables that can be reassigned, and const is a keyword that is used to declare variables that cannot be reassigned.

9. What Is The Difference Between An Array And A Tuple?

A Tuple is a data structure that is similar to an array but with a few key differences. For one, Tuples are immutable, meaning they cannot be changed. This is in contrast to arrays, which are mutable and can be changed in place. Secondly, Tuples are typically used to store related data, while arrays are more often used to store unrelated data. Finally, Tuples are usually created with parentheses, while arrays are usually created with square brackets.

10. What Is The Difference Between A Class And A Struct?

When it comes to classes and Structs, there is one key difference that sets them apart: classes are reference types, while Structs are value types.

This means that when you create an instance of a class, you are actually creating a reference to an object. That reference is then stored in the variable. On the other hand, when you create an instance of a Struct, the actual Struct is copied and stored in the variable.

This has a few implications. For one, it means that when you pass an instance of a class to a method, the method can modify the underlying object. However, when you pass an instance of a Struct to a method, the method can only modify a copy of the Struct.

Another implication is that classes can be null, while Structs cannot. This is because a class variable can store a reference to null, whereas a Struct variable will always contain a valid instance of the Struct.

Overall, the key difference between classes and Structs is that classes are reference types and Structs are value types.

11. What Is The Difference Between An Interface And A Type?

An interface is a description of a set of related behaviors, while a type is a specific implementation of an interface. In other words, an interface defines how something should work, while a type defines a specific way of implementing that interface.

12. What Is The Difference Between A Namespace And A Module?

A namespace is a way of organizing code so that it is easy to find and reuse. Namespaces are often used to group together related code, such as all the code related to a particular project or task.

A module, on the other hand, is a self-contained piece of code that can be reused in different projects or tasks. Modules are often written so that they can be easily plugged into different codebases.

So, to recap:

  • A namespace is a way of organizing code.
  • A module is a self-contained piece of code that can be reused.

13. What Is The Difference Between An Enum And A Union Type?

Enums are used to represent a finite set of values, while union types are used to represent a set of values that can take on multiple different types.

Enums are often used to represent things like days of the week, where there are only a finite number of values that can be represented. Union types, on the other hand, are often used to represent data that can take on multiple different types. For example, a union type could be used to represent a value that could either be an integer or a string.

So, in short, the key difference between Enums and union types is that Enums are used to represent a finite set of values, while union types are used to represent a set of values that can take on multiple different types.

14. What Is The Difference Between A Type And A Keyword?

There is a big difference between types and keywords when it comes to blogging. First, types are usually much longer and more detailed than keywords. Secondly, keywords are typically used more for search engine optimization (SEO) purposes than types. Finally, keywords are often more specific than types, making them better suited for targeted audiences.

15. What Is The Difference Between An Abstract Class And An Interface?

An abstract class is a class that contains one or more abstract methods. An abstract method is a method that is declared but not implemented in the code. An interface is a contract between two pieces of code that specifies the methods that one piece of code will make available to the other piece of code.

16. What Is The Difference Between A Static And An Instance Method?

Static methods are those that are associated with a class, but not with any specific instance of that class. This means that they can be called without having to create an instance of the class first. On the other hand, instance methods are those that are associated with a specific instance of a class. This means that they can only be called after an instance of the class has been created.

17. What Is The Difference Between A Static And An Instance Property?

When it comes to static and instance properties, there is one key difference that sets them apart. Static properties are associated with a class, while instance properties are associated with an instance of a class. This means that static properties can be accessed without having an instance of the class, while instance properties can only be accessed through an instance of the class.

18. What Is The Difference Between A String And A Number?

The string is a sequence of characters, while a number is a mathematical value.  A string can be any sequence of characters, including letters, numbers, and special characters. A number, on the other hand, is a mathematical value that can be used in calculations.

19. What Is The Difference Between A Null And An Undefined Value?

The null value is an explicit representation of no value, while an undefined value is an implicit representation of no value. In other words, a null value is a value that has been explicitly set to no value, while an undefined value is a value that has not been explicitly set to any value.

20. What Is The Difference Between An Element And A Node?

An element is a part of a larger whole, while a node is a point of connection between elements. In other words, an element is a building block, while a node is a junction point.

21. What Is The Object Type In Typescript?

When I was preparing for my TypeScript interview, I looked up the object type on the TypeScript website. The object type in TypeScript is a type that represents any non-primitive value. This includes objects, arrays, functions, and even user-defined types. The object type is a super-type of all other types, and thus, any value can be assigned to a variable of type object.

22. What Is The Typescript Compiler?

The TypeScript compiler is a tool that helps developers write code in the TypeScript programming language. The compiler converts TypeScript code into JavaScript code that can be run in web browsers and other JavaScript environments.

I’ve been using the TypeScript compiler for a few months now, and I’ve found it to be a valuable tool for writing code. The compiler has helped me catch errors in my code, and it has also helped me improve my code quality.

23. What Is The Void Type In Typescript?

When I was preparing for my TypeScript interview, I came across the concept of the void type. Void is a type that can only be assigned the value undefined or null. It’s a little bit like the opposite of any, in that it can’t be assigned any other values. Void is often used as the return type of function that doesn’t return anything. This is because, in JavaScript, a function doesn’t have to explicitly return anything – if you don’t specify a return value, it will return undefined automatically. So, using void as the return type of a function is a way of indicating that the function doesn’t return anything explicitly.

There are other uses for void as well. For example, you could use it as the type of variable that will never have a value. This can be useful in cases where you want to make sure that a variable can never be anything other than undefined or null.

24. What Is The Null Type In Typescript?

The null type is really useful for cases when you need a value that can be either null or not null. For example, you might want to use a nullable string to represent a person’s middle name, since not everyone has one. Or you might want to use a nullable Boolean to represent whether or not a user is logged in, since it can be either true (logged in) or false (not logged in).

Nullable types are actually a bit of a misnomer since they can also be undefined. However, in TypeScript, null and undefined are considered two different types, so a nullable type can only be null or undefined, not both.

There are two ways to create nullable types in TypeScript. The first is to use the “?” symbol, like this:

var middlegame: string? = “Jane”;

This declares a variable called “middlegame” which can be either a string or null. The second way is to use the “null” keyword:

var is logged in: boolean = null;

This declares a variable called “is logged in” which can be either true or false, but not null.

Nullable types are really useful when you need to represent a value that can be either null or not null. However, you should be careful not to overuse them, as they can make your code harder to read and understand.

25. What Are The Symbol Types In Typescript?

There are many symbol types in TypeScript, but the most common ones are,

  • String Symbols

These are symbols that represent a string of characters. For example, “hello” is a string symbol.

  • Number Symbols

These are symbols that represent a number. For example, 42 is a number symbol.

  • Boolean Symbols

These are symbols that represent a Boolean value (true or false). For example, true is a Boolean symbol.

  • Null Symbols

These are symbols that represent the value null. For example, null is a null symbol.

  • Undefined Symbols

These are symbols that represent the value undefined. For example, undefined is an undefined symbol.

Conclusion

I was so excited to receive an email notification that I had received a TypeScript interview invitation. After reading the job posting and reviewing the code samples, I felt confident that I would be able to answer all of the questions. The interview process was structured in such a way that it allowed me to practice my responses multiple times beforehand. Although some of the questions were more challenging than others, I was still able to provide thorough and accurate answers. Overall, I thought the experience was extremely positive, and am grateful for the opportunity to have interviewed with this company.

Recent Posts