MCQs on Meta-Programming and TypeScript | TypeScript
Dive into 30 MCQs on Meta-Programming and TypeScript, covering advanced reflection techniques, proxies, metadata, and decorators. Master how TypeScript enhances your code’s flexibility with these powerful tools.
Chapter 24: Meta-Programming and TypeScript
Advanced Reflection Techniques
- What is reflection in TypeScript?
- a) The ability to modify the structure of a program at runtime
- b) The process of inspecting and manipulating objects and types
- c) A form of automatic code generation
- d) Using JavaScript to inspect TypeScript types
- Which of the following is an example of reflection in TypeScript?
- a)
Reflect.construct() - b)
new MyClass() - c)
typeOf() - d)
Object.getPrototypeOf()
- a)
- How does
ReflectAPI help in TypeScript meta-programming?- a) It helps with manipulating object properties at runtime
- b) It provides a mechanism for reflection in runtime
- c) It allows static type checking
- d) It automatically converts JavaScript code to TypeScript
- Which method in the
ReflectAPI is used to get metadata for a class or property?- a)
Reflect.get() - b)
Reflect.getMetadata() - c)
Reflect.defineMetadata() - d)
Reflect.define()
- a)
- How can reflection techniques improve debugging in TypeScript applications?
- a) By allowing access to the internal properties of objects
- b) By simplifying class inheritance
- c) By automatically refactoring code
- d) By adding runtime performance enhancements
- What does
Reflect.getOwnMetadata()do in TypeScript?- a) It retrieves metadata for a property defined on the class
- b) It adds metadata to a class or property
- c) It updates the class constructor’s metadata
- d) It defines metadata for a class’s method
- Which TypeScript library is often used with reflection for advanced techniques?
- a)
reflect-metadata - b)
typescript-reflect - c)
type-metadata - d)
ts-metadata
- a)
- In TypeScript, what is the role of
Reflect.defineMetadata()?- a) To define metadata for classes, properties, or methods at runtime
- b) To create new classes dynamically
- c) To update type definitions at runtime
- d) To reflect property changes at compile-time
- How does reflection help in dynamic class instantiation in TypeScript?
- a) By enabling the creation of class instances using reflection techniques
- b) By auto-generating constructors
- c) By ensuring type safety during instantiation
- d) By optimizing memory management at runtime
- What is a primary use case for advanced reflection techniques in TypeScript?
- a) To access private properties and methods dynamically
- b) To define class constructors at runtime
- c) To enable multi-threading in JavaScript
- d) To compile TypeScript code to JavaScript
Using Proxy and Metadata in TypeScript
- What is a Proxy in TypeScript?
- a) An object that allows you to define custom behavior for fundamental operations
- b) A tool to minify code
- c) A type of variable that can be used only in asynchronous operations
- d) A reflection method for classes
- How is a Proxy used in TypeScript?
- a) By intercepting and modifying operations on objects
- b) By creating private methods
- c) By compiling TypeScript code to JavaScript
- d) By handling exceptions globally
- What are the basic methods provided by the
Proxyobject in TypeScript?
- a)
get(),set(),delete() - b)
intercept(),hook(),trap() - c)
run(),stop(),pause() - d)
start(),end(),clear()
- What type of behavior can be customized using a Proxy in TypeScript?
- a) Property access, assignment, and deletion
- b) Compilation of TypeScript files
- c) Event handling in HTML
- d) Automatic garbage collection
- What is metadata in TypeScript?
- a) Information that provides context about class members at runtime
- b) Type annotations for variables
- c) The configuration file for TypeScript projects
- d) Data about code performance
- How is metadata typically used in conjunction with proxies in TypeScript?
- a) By attaching additional data to objects for later reflection
- b) By monitoring object types during compilation
- c) By controlling object creation processes
- d) By compiling proxies to JavaScript
- What is a common use case for proxies in TypeScript?
- a) To create objects with dynamic behaviors
- b) To manage event listeners in the browser
- c) To optimize runtime performance
- d) To manage memory leaks
- Which of the following is a benefit of using proxies in TypeScript?
- a) Ability to intercept and modify fundamental operations on objects
- b) Reduced code size
- c) Enhanced performance for large applications
- d) Automatic error handling for API calls
- Which function is used to create a Proxy object in TypeScript?
- a)
new Proxy() - b)
Reflect.Proxy() - c)
Proxy.create() - d)
Proxy.createObject()
- In TypeScript, what kind of object can be proxied?
- a) Any object
- b) Only class instances
- c) Only arrays
- d) Only functions
Advanced Use of Decorators for Meta-Programming
- What is a decorator in TypeScript?
- a) A function that is applied to a class or method at design-time
- b) A way to enhance JavaScript functions dynamically
- c) A utility to manage metadata during compilation
- d) A way to generate runtime code
- How are decorators typically used in TypeScript?
- a) To modify or enhance the behavior of classes and class members
- b) To optimize functions
- c) To add types to JavaScript code
- d) To handle HTTP requests
- Which decorator is used to define a method in TypeScript?
- a)
@method() - b)
@property() - c)
@target() - d)
@decorator()
- What is the purpose of a class decorator in TypeScript?
- a) To modify or enhance the behavior of a class
- b) To optimize class instantiation
- c) To add metadata to the class at compile-time
- d) To define the class’s constructor
- How do you create a parameter decorator in TypeScript?
- a) By using the
@parameterDecorator(parameterIndex)syntax - b) By using the
@method()decorator - c) By creating a custom metadata class
- d) By annotating the parameter type with
@param()
- What is the main benefit of using decorators in meta-programming?
- a) Ability to add metadata to classes and methods
- b) Automatic memory management
- c) Reduces file size in TypeScript
- d) Enhances the speed of method execution
- How can decorators be used with class properties in TypeScript?
- a) By defining property-specific behavior and metadata
- b) By compiling the class into JavaScript
- c) By optimizing property access times
- d) By assigning default values to properties
- Which decorator type is used to apply metadata to method parameters?
- a) Parameter decorator
- b) Property decorator
- c) Class decorator
- d) Method decorator
- How can metadata be accessed in TypeScript using decorators?
- a) Using the
ReflectAPI - b) Using the
@metadata()decorator - c) By inspecting the TypeScript compiler output
- d) By using custom reflection methods
- What is the primary purpose of advanced decorators in TypeScript meta-programming?
- a) To modify class behavior, define metadata, and provide additional functionality
- b) To perform automatic code generation
- c) To enhance the performance of JavaScript engines
- d) To create dynamic code for the backend
Answer Key
| Qno | Answer |
|---|---|
| 1 | b) The process of inspecting and manipulating objects and types |
| 2 | a) Reflect.construct() |
| 3 | b) It provides a mechanism for reflection in runtime |
| 4 | b) Reflect.getMetadata() |
| 5 | a) By allowing access to the internal properties of objects |
| 6 | a) It retrieves metadata for a property defined on the class |
| 7 | a) reflect-metadata |
| 8 | a) To define metadata for classes, properties, or methods at runtime |
| 9 | a) By enabling the creation of class instances using reflection techniques |
| 10 | a) To access private properties and methods dynamically |
| 11 | a) An object that allows you to define custom behavior for fundamental operations |
| 12 | a) By intercepting and modifying operations on objects |
| 13 | a) get(), set(), delete() |
| 14 | a) Property access, assignment, and deletion |
| 15 | a) Information that provides context about class members at runtime |
| 16 | a) By attaching additional data to objects for later reflection |
| 17 | a) To create objects with dynamic behaviors |
| 18 | a) Ability to intercept and modify fundamental operations on objects |
| 19 | a) new Proxy() |
| 20 | a) Any object |
| 21 | a) A function that is applied to a class or method at design-time |
| 22 | a) To modify or enhance the behavior of classes and class members |
| 23 | a) @method() |
| 24 | a) To modify or enhance the behavior of a class |
| 25 | a) By using the @parameterDecorator(parameterIndex) syntax |
| 26 | a) Ability to add metadata to classes and methods |
| 27 | a) By defining property-specific behavior and metadata |
| 28 | a) Parameter decorator |
| 29 | a) Using the Reflect API |
| 30 | a) To modify class behavior, define metadata, and provide additional functionality |