Generics

📘 手冊

• TypeScript ⟩ Generic Object Types

📗 參考

• Swift ⟩ Generics

👥 相關

• ⭐️ Cheat sheet

Cheatsheet

/* ------- ⭐️ Generic type alias -------- */

// ⭐️ generic types
type Optional<T> = T | null;
type OneOrMany<T> = T | T[];
type OptioanlOneOrMany<T> = Optional<OneOrMany<T>>;  // T | T[] | null

// ⭐️ concrete type
type OptionalOneOrManyStrings = OptioanlOneOrMany<string>;
// string | string[] | null

type Box<T> = { contents: T; };


/* ------- ⭐️ Generic interface -------- */

interface Box<T> {        // `T`: type parameter
  contents: T;
}

let box: Box<string>;     // `string`: type argument


/* ------- ⭐️ Generic functions -------- */

function setContents<T>(box: Box<T>, contents: T) {
  box.contents = contents;
}

Topics

• Generic Functions

• Array<T>

types like Map<K, V>, Set<T>, and Promise<T> are also generic.