Intersection type syntax in Typescript - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a variable with an intersection type of Person and Employee.

Typescript

type Person = { name: string };
type Employee = { id: number };
let worker: Person [1] Employee;

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

A&

B|

C,

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using '|' instead of '&' which creates a union type.

Using ',' or '+' which are invalid in type declarations.

The intersection type uses the '&' symbol to combine types so the variable has all properties.

2fill in blank

medium

Complete the code to define a function parameter with an intersection type of A and B.

Typescript

type A = { a: number };
type B = { b: string };
function combine(param: A [1] B) {
  console.log(param.a, param.b);
}

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

A|

B&

C/

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using '|' which allows either type but not both.

Using invalid symbols like '/' or '+'.

The function parameter uses '&' to require both A and B properties.

3fill in blank

hard

Fix the error in the intersection type declaration.

Typescript

type X = { x: number } [1] { y: string };

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

A|

B+

C,

D&

Attempts:

3 left

💡 Hint

Common Mistakes

Using '|' which creates a union type.

Using ',' or '+' which are invalid here.

The correct intersection operator is '&' to combine the two object types.

4fill in blank

hard

Fill both blanks to create an intersection type combining interfaces A and B.

Typescript

interface A { a: number; }
interface B { b: string; }
type AB = [1] A [2] B;

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

Atype

B&

C|

Dinterface

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'interface' instead of 'type' for intersection types.

Using '|' instead of '&' to combine types.

Use 'type' to declare a type alias and '&' to combine interfaces A and B.

5fill in blank

hard

Fill all three blanks to create a variable with an intersection type and assign a valid object.

Typescript

type C = { c: boolean };
type D = { d: number };
let obj: [1] = { c: true, d: 42 } as [2] [3] D;

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

AC & D

BC

C&

DD

Attempts:

3 left

💡 Hint

Common Mistakes

Using only one type without intersection.

Using '|' instead of '&' for intersection.

The variable obj is declared with type 'C & D' and cast as 'C & D' to satisfy both types.