Whether you're just starting your career or looking to level up in the tech industry, mastering TypeScript is crucial. If you're a fresher or an experienced professional preparing for jobs that require typescript skills, here's a guide for you. In this article, we have compiled the 25 commonly asked Typescript interview questions, along with some basic questions, and provided sample answers.
1. What do you know about TypeScript?
TypeScript is a superset of JavaScript that adds static typing and other features to the language. It compiles down to plain JavaScript, making it compatible with all major browsers.
2. What are the key features of TypeScript?
Some key features of TypeScript include static typing, classes and interfaces, modules and namespaces, decorators, generics, and support for modern JavaScript features.
3. What is the advantage of using TypeScript over JavaScript?
TypeScript offers advantages such as type checking at compile time, which helps catch errors early, better tooling support with autocompletion and refactoring capabilities, improved code maintainability with the use of classes and interfaces, and compatibility with existing JavaScript codebases.
4. How do you define variables in TypeScript?
In TypeScript, variables can be defined using the 'let' or 'const' keywords.
For example: let age: number = 25; const name: string = "John";
5. Explain what is meant by static typing in TypeScript.
Static typing in TypeScript ensures that variables have specific types assigned to them at compile-time. This helps detect type-related errors before runtime and provides better code documentation.
6. How do you declare an array in TypeScript?
Arrays can be declared in TypeScript using square brackets [] after the variable name, followed by the desired type within angle brackets <>.
For example: let numbers: number[] = [1, 2, 3];
7. What are interfaces in TypeScript?
Interfaces define the structure of objects in TypeScript by specifying properties and their types. They help enforce contracts between different parts of an application.
8. How do you implement inheritance in TypeScript?
Inheritance can be implemented in TypeScript using the 'extends' keyword followed by the parent class name after declaring a child class. For example: class
ChildClass extends ParentClass {}
9. What is a module in TypeScript?
Modules in TypeScript are a way to organise and reuse code. They allow you to split your code into separate files and export and import functionality between them.
10. How do you handle asynchronous operations in TypeScript?
Asynchronous operations can be handled using promises or async/await syntax in TypeScript. Promises provide a way to work with asynchronous data, while async/await simplifies the syntax for writing asynchronous code.
11. Explain the difference between 'undefined' and 'null' in TypeScript.
'Undefined' represents a variable that has been declared but not assigned any value, while 'null' represents the deliberate assignment of no value to a variable.
12. What are generics in TypeScript?
Generics allow you to create reusable components that can work with different types without sacrificing type safety. They provide a way to define placeholders for types that are specified when using the component.
13. How do you handle errors in TypeScript?
Errors can be handled using try-catch blocks in TypeScript, similar to JavaScript. Errors thrown within the try block can be caught and handled in the catch block.
14. Explain what is meant by decorators in TypeScript.
Decorators are a feature of TypeScript that allows you to modify or extend the behaviour of classes, methods, properties, or parameters at design time. They enable you to add metadata and configure aspects of your code.
15. How do you define optional parameters in TypeScript functions?
Optional parameters can be defined by appending a question mark '?' after the parameter name during function declaration. For example: function greet(name?: string) {}
16. What is type assertion in TypeScript?
Type assertion is a way to tell the compiler about the type of a variable when there is more information available than what's inferred by default.
17. How do you implement dependency injection in TypeScript?
Dependency injection can be implemented in TypeScript by using a framework or by manually creating and injecting dependencies into classes.
18. What is the purpose of the 'readonly' keyword in TypeScript?
The 'readonly' keyword in TypeScript is used to define properties that cannot be modified once they are assigned a value.
19. How do you configure TypeScript compiler options?
TypeScript compiler options can be configured using a tsconfig.json file, which allows you to specify various settings such as target JavaScript version, output directory, and module resolution.
20. Explain what is meant by two-way data binding in Angular with TypeScript.
Two-way data binding in Angular with TypeScript allows for automatic synchronisation between the model (component) and the view (template). Changes made in one are automatically reflected in the other.
21. What is an abstract class in TypeScript?
An abstract class is a class that cannot be instantiated directly and is meant to serve as a base class for other classes. It can contain method declarations without providing implementations.
22. How do you handle exceptions in TypeScript?
Exceptions can be handled using try-catch blocks similar to JavaScript. Code that might throw an exception is placed within the try block, and any exceptions are caught and handled in the catch block.
23. Explain what access modifiers are in TypeScript.
Access modifiers control the visibility of properties and methods within a class. TypeScript supports three access modifiers: public, private, and protected.
24. What are union types in TypeScript?
Union types allow variables or parameters to hold values of different types. They are denoted by the pipe '|' symbol between type names.
25. What are type guards in TypeScript?
Type guards are used to narrow down the type of a variable within a conditional block, allowing for more precise type checking and enabling access to specific properties or methods.
Mastering Typescript Interview Questions
By understanding Typescript's nuances and being well-prepared for interview questions specific to this language, you can set yourself apart from the competition. If you're looking for expert guidance on upskilling programmes to enhance your career prospects in Typescript or any other field, WiZR is here for you.
FAQs
1. Which professionals use typescript?
Typescript is widely used by web developers, software engineers, front-end developers, full-stack developers, and anyone working with JavaScript frameworks like Angular or React.
2. Is typescript more difficult to learn than Javascript?
While Typescript builds upon JavaScript, it does introduce additional features and concepts, such as static typing. It may require some extra effort to learn, but it offers benefits like improved code safety and a better developer experience.
3. What courses are available for Typescript?
There are several online platforms and institutes offering courses on Typescript. These courses range from beginner-level introductions to advanced topics on building scalable applications.
4. When will I require upskilling programmes in Typescript?
Upskilling programmes in Typescript becomes necessary when you want to advance your career or switch roles that specifically require expertise in this language. They can help you gain a competitive edge and open doors to new opportunities in the ever-evolving tech industry.
