Generic function syntax in Typescript - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a generic function named identity.

Typescript

function identity[1](arg: T): T {
  return arg;
}

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A<T>

B(T)

C[T]

D{T}

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses or square brackets instead of angle brackets for generic parameters.

Forgetting to add the generic parameter after the function name.

Generic functions use angle brackets <> to declare type parameters.

2fill in blank

medium

Complete the code to call the generic function identity with a string argument.

Typescript

let output = identity[1]("hello");

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A[string]

B(string)

C{string}

D<string>

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses instead of angle brackets to specify the type argument.

Omitting the type argument when calling the generic function.

When calling a generic function, specify the type argument inside angle brackets.

3fill in blank

hard

Fix the error in the generic function declaration by completing the missing generic parameter syntax.

Typescript

function getArray[1](items: T[]): T[] {
  return new Array().concat(items);
}

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A<T>

B(T)

C[T]

D{T}

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses or braces instead of angle brackets for generic parameters.

Forgetting to declare the generic parameter.

Generic parameters must be declared inside angle brackets after the function name.

4fill in blank

hard

Fill both blanks to declare a generic function wrapInArray that takes a value and returns it inside an array.

Typescript

function wrapInArray[1](value: [2]): [2][] {
  return [value];
}

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A<T>

BT

CU

Dany

Attempts:

3 left

💡 Hint

Common Mistakes

Using different generic type names for argument and return type.

Not declaring the generic parameter.

Declare the generic parameter <T> and use T as the type for the argument and return array.

5fill in blank

hard

Fill all three blanks to declare a generic function merge that takes two objects and returns their merged result.

Typescript

function merge[1](obj1: [2], obj2: [3]): [2] & [3] {
  return { ...obj1, ...obj2 };
}

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

A<T, U>

BT

CU

Dobject

Attempts:

3 left

💡 Hint

Common Mistakes

Using the same generic type for both arguments.

Not declaring generic parameters properly.

Declare two generic parameters <T, U> and use them as types for the two arguments and the return type as their intersection.