Generic class syntax in Typescript - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a generic class named Box.

Typescript

class Box[1] {
  content: T;
  constructor(value: T) {
    this.content = value;
  }
}

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

A(T)

B<T>

C[T]

D{T}

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses or braces instead of angle brackets for generics.

Forgetting to add the generic parameter after the class name.

In TypeScript, generic classes use angle brackets after the class name to declare a type parameter.

2fill in blank

medium

Complete the code to create an instance of the generic class Box with type number.

Typescript

const numberBox = new Box[1](123);

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A<string>

B<any>

C<boolean>

D<number>

Attempts:

3 left

💡 Hint

Common Mistakes

Using a type that does not match the value passed to the constructor.

Omitting the generic type parameter.

To create a generic class instance with a specific type, use angle brackets with the type after the class name.

3fill in blank

hard

Fix the error in the generic class declaration by completing the blank.

Typescript

class Pair[1] {
  first: T;
  second: U;
  constructor(first: T, second: U) {
    this.first = first;
    this.second = second;
  }
}

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A<T, U>

B<T>

C<U>

D<T U>

Attempts:

3 left

💡 Hint

Common Mistakes

Using only one generic parameter when two are needed.

Missing the comma between generic parameters.

When declaring multiple generic types, separate them with commas inside angle brackets like .

4fill in blank

hard

Fill both blanks to declare a generic class with two type parameters and a method returning the first value.

Typescript

class Container[1] {
  value1: T;
  value2: U;
  constructor(v1: T, v2: U) {
    this.value1 = v1;
    this.value2 = v2;
  }
  getFirst(): [2] {
    return this.value1;
  }
}

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

A<T, U>

BT

CU

Dany

Attempts:

3 left

💡 Hint

Common Mistakes

Using only one generic parameter in the class declaration.

Returning the wrong generic type in the method.

The class declares two generic types . The method getFirst returns the first value of type T.

5fill in blank

hard

Fill all three blanks to create a generic class with a method that swaps two values and returns a tuple.

Typescript

class Swapper[1] {
  a: T;
  b: U;
  constructor(a: T, b: U) {
    this.a = a;
    this.b = b;
  }
  swap(): [[2], [3]] {
    return [this.b, this.a];
  }
}

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

A<T, U>

BT

CU

Dany

Attempts:

3 left

💡 Hint

Common Mistakes

Returning the tuple with the same order of types instead of swapped.

Using incorrect generic type syntax.

The class uses two generic types . The swap method returns a tuple with types [U, T], swapping the order.