Generic factory pattern in Typescript - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a generic factory function that returns an instance of type T.

Typescript

function createInstance<T>(ctor: { new(): [1] }): T {
  return new ctor();
}

Drag options to blanks, or click blank then click option'

Aobject

Bvoid

Cany

DT

Attempts:

3 left

💡 Hint

Common Mistakes

Using a fixed type like 'object' instead of the generic type T.

Omitting the return type in the constructor signature.

The generic type T is used to specify the return type of the factory function. The constructor signature must return T to create an instance of that type.

2fill in blank

medium

Complete the code to define a generic factory interface with a create method.

Typescript

interface Factory<T> {
  create(): [1];
}

Drag options to blanks, or click blank then click option'

Avoid

Bany

CT

Dobject

Attempts:

3 left

💡 Hint

Common Mistakes

Using void as the return type which means no value is returned.

Using any which loses type safety.

The create method should return an instance of the generic type T.

3fill in blank

hard

Fix the error in the generic factory function signature to correctly accept a constructor.

Typescript

function factory<T>([1]: { new(): T }): T {
  return new ctor();
}

Drag options to blanks, or click blank then click option'

Actor

Bcreate

Cinstance

Dobj

Attempts:

3 left

💡 Hint

Common Mistakes

Using a parameter name different from the one used inside the function body.

Omitting the parameter name.

The parameter name ctor is used to represent the constructor function. It must match the name used inside the function body.

4fill in blank

hard

Fill both blanks to create a generic factory function that accepts a constructor and returns an instance.

Typescript

function create[1]<T>([2]: { new(): T }): T {
  return new ctor();
}

Drag options to blanks, or click blank then click option'

AInstance

BFactory

Cctor

Dobj

Attempts:

3 left

💡 Hint

Common Mistakes

Using inconsistent parameter names.

Using a function name that does not describe its purpose.

The function name createFactory describes the factory pattern. The parameter ctor is the constructor used to create the instance.

5fill in blank

hard

Fill all three blanks to implement a generic factory class with a create method.

Typescript

class Generic[1]<T> {
  constructor(private [2]: { new(): T }) {}
  create(): [3] {
    return new this.ctor();
  }
}

Drag options to blanks, or click blank then click option'

AFactory

Bctor

CT

DInstance

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect class or parameter names.

Not using the generic type T consistently.

The class is named GenericFactory. The constructor parameter ctor is the constructor function. The create method returns an instance of type T.