TypeScript Interview Questions and Answers
Intermediate / 1 to 5 years experienced level questions & answers
Ques 1. Explain the concept of static typing in TypeScript.
Static typing in TypeScript involves specifying the data types of variables at compile time, which helps catch type-related errors early in the development process.
Ques 2. Explain the 'this' keyword in TypeScript.
The 'this' keyword in TypeScript is used to refer to the current instance of the object within a class or function.
Ques 3. What is a module in TypeScript?
A module in TypeScript is a way to organize code into separate files, and it can include interfaces, classes, functions, and variables.
Ques 4. What is the use of 'namespace' in TypeScript?
The 'namespace' keyword in TypeScript is used to group related code into a named scope, preventing naming conflicts with other parts of the program.
Ques 5. Explain the 'async' and 'await' keywords in TypeScript.
'async' is used to declare an asynchronous function, and 'await' is used to pause the execution of the function until the promise is resolved.
Ques 6. What are decorators in TypeScript?
Decorators are a special kind of declaration that can be attached to classes, methods, and properties to modify their behavior.
Ques 7. What is the difference between 'interface' and 'type' in TypeScript?
'interface' is used for object shapes, while 'type' can be used for objects, unions, intersections, and primitives.
Ques 8. Explain the concept of generics in TypeScript.
Generics in TypeScript allow you to write functions and classes that can work with any data type.
Ques 9. How does TypeScript achieve type inference?
TypeScript uses a mechanism called type inference to automatically determine and assign types to variables based on their values and usage.
Ques 10. What are type guards in TypeScript?
Type guards are expressions that help TypeScript narrow down the type of a variable within a certain code block.
Ques 11. What is the 'keyof' operator in TypeScript?
The 'keyof' operator in TypeScript is used to obtain the union type of all possible keys of an object type.
Ques 12. Explain the concept of declaration merging in TypeScript.
Declaration merging in TypeScript allows multiple declarations for the same entity to be combined into a single entity.
Ques 13. How do you use the 'as' keyword for type assertions in TypeScript?
The 'as' keyword in TypeScript is used for type assertions, allowing you to tell the compiler that you know more about the type of a value than it does.
Ques 14. Explain the concept of ambient declarations in TypeScript.
Ambient declarations in TypeScript are used to tell the compiler about the existence of external entities, such as libraries or globals, that are not defined in the current TypeScript file.
Ques 15. How do you create an instance of an interface in TypeScript?
Interfaces in TypeScript are not directly instantiated. Instead, you can create an object literal that conforms to the shape of the interface.
Ques 16. What is the 'this' type in TypeScript?
The 'this' type in TypeScript is used to represent the type of the instance of a class or object within a method.
Ques 17. Explain the concept of abstract classes in TypeScript.
Abstract classes in TypeScript are classes that cannot be instantiated on their own and are meant to be subclassed. They may contain abstract methods that must be implemented by subclasses.
Ques 18. What is the purpose of the 'namespace' keyword in TypeScript?
The 'namespace' keyword in TypeScript is used to group related code into a named scope, preventing naming conflicts with other parts of the program.
Ques 19. How do you use the 'readonly' modifier with arrays and objects?
The 'readonly' modifier in TypeScript can be applied to arrays and objects using 'ReadonlyArray
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