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Learning TypeScript 2.x - Second Edition
book

Learning TypeScript 2.x - Second Edition

by Remo H. Jansen
April 2018
Beginner content levelBeginner
536 pages
13h 21m
English
Packt Publishing
Content preview from Learning TypeScript 2.x - Second Edition

Built-in conditional types

In the preceding section, we have used the ReturnType type to extract the return type of a given function. The ReturnType type is included as a built-in type. TypeScript 2.8 includes many other types:

// Exclude from T those types that are assignable to Utype Exclude<T, U> = T extends U ? never : T;// Extract from T those types that are assignable to Utype Extract<T, U> = T extends U ? T : never;// string[] | number[]type Foo2 = Extract<boolean | string[] | number[], any[]>;// booleantype Bar2 = Exclude<boolean | string[] | number[], any[]>;// Exclude null and undefined from Ttype NonNullable<T> = T extends null | undefined ? never : T;//  Obtain the return type of a function typetype ReturnType<T extends (...args: ...
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Publisher Resources

ISBN: 9781788391474Supplemental Content