Exclude type in Typescript - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to exclude the type 'string' from the union.

Typescript

type Result = Exclude<string | number | boolean, [1]>;

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Astring

Bboolean

Cnumber

Dany

Attempts:

3 left

💡 Hint

Common Mistakes

Using a type that is not in the union to exclude.

Confusing Exclude with Extract.

The Exclude type removes the specified type from the union. Here, 'string' is excluded.

2fill in blank

medium

Complete the code to exclude 'null' and 'undefined' from the type.

Typescript

type NonNullableType = Exclude<string | null | undefined, [1]>;

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Anull | undefined

Bstring

Cnull

Dundefined

Attempts:

3 left

💡 Hint

Common Mistakes

Excluding only one of the types instead of both.

Using a single type instead of a union.

Exclude removes all types in the second parameter from the first union type. Here, both 'null' and 'undefined' are excluded.

3fill in blank

hard

Fix the error in excluding 'number' from the union type.

Typescript

type CleanType = Exclude<string | number | boolean, [1]>;

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Aboolean

Bnumber

Cstring

Dnever

Attempts:

3 left

💡 Hint

Common Mistakes

Excluding a type not present in the union.

Using 'never' which excludes nothing.

To exclude 'number' from the union, you must specify 'number' as the second parameter.

4fill in blank

hard

Fill both blanks to exclude 'string' and 'boolean' from the union.

Typescript

type Filtered = Exclude<[1], [2]>;

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Astring | number | boolean

Bstring | boolean

Cnumber | boolean

Dstring | number

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping the two blanks.

Excluding types not in the original union.

The first blank is the original union type. The second blank is the union of types to exclude.

5fill in blank

hard

Fill all three blanks to exclude 'null' and 'undefined' from the union.

Typescript

type Cleaned = Exclude<[1], [2] | [3]>;

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Astring | number | boolean | null | undefined | false

Bnull

Cundefined

Dfalse

Attempts:

3 left

💡 Hint

Common Mistakes

Not including all types in the first blank.

Excluding only some of the unwanted types.

The first blank is the full union type. The second and third blanks are types to exclude combined with '|'.