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Programming TypeScript
book

Programming TypeScript

by Boris Cherny
May 2019
Intermediate to advanced content levelIntermediate to advanced
322 pages
7h 6m
English
O'Reilly Media, Inc.
Book available
Content preview from Programming TypeScript

Appendix B. Type Utilities

TypeScript’s type utilities come bundled into its standard library. Table B-1 enumerates all of the available utilities at the time of writing.

See es5.d.ts for an up-to-date reference.

Table B-1. Type utilities
Type utility Use it on Description

ConstructorParameters

Class constructor types

A tuple of a class constructor’s parameter types

Exclude

Union types

Exclude a type from another type

Extract

Union types

Select a subtype that’s assignable to another type

InstanceType

Class constructor types

The instance type you get from new-ing a class constructor

NonNullable

Nullable types

Exclude null and undefined from a type

Parameters

Function types

A tuple of a function’s parameter types

Partial

Object types

Make all properties in an object optional

Pick

Object types

A subtype of an object type, with a subset of its keys

Readonly

Array, Object, and Tuple types

Make all properties in an object read-only, or make an array or tuple read-only

ReadonlyArray

Any type

Make an immutable array of the given type

Record

Object types

A map from a key type to a value type

Required

Object types

Make all properties in an object required

ReturnType

Function types

A function’s return type

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Publisher Resources

ISBN: 9781492037644Errata PageSupplemental Content