Dictionary Types

Convenient type definitions for commonly used dictionary/map style objects in TypeScript.

Deprecated

Since TypeScript 2.1, TypeScript has a built-in Record type which renders this package obsolete. Consider also using an ES6 Map instead.

Instead of Dictionary<T>, use Record<string, T> or Map<string, T>.
Instead of Dictionary<T, K>, use Record<K, T> or Map<K, T>.
Instead of ReadonlyDictionary<T>, use Readonly<Record<string, T>> or ReadonlyMap<string, T>.
Instead of ReadonlyDictionary<T, K>, use Readonly<Record<K, T>> or ReadonlyMap<K, T>.
Instead of NumberMap<T>, use Record<number, T> or Map<number, T>.
Instead of ReadonlyNumberMap<T>, use Readonly<Record<number, T>> or ReadonlyMap<number, T>.

Installation and usage

npm install --save dictionary-types

import {
    Dictionary,
    ReadonlyDictionary,
    NumberMap,
    ReadonlyNumberMap
} from "dictionary-types";

Dictionary<T>

An object containing elements of type T, keyed by string.

const scores: Dictionary<number> = {
    "Amelia": 4,
    "Riley": 7,
    "April": 5
};

scores["Xander"] = 3;

Dictionary<TValue, TKey>

An object containing elements of type TValue, keyed by TKey.

const amelia = Symbol();
const riley = Symbol();
const april = Symbol();
const xander = Symbol();

type Participant = typeof amelia | typeof riley | typeof april | typeof xander;

const scores: Dictionary<number, Participant> = {
    [amelia]: 4,
    [riley]: 7,
    [april]: 5
};

scores[xander] = 3;

ReadonlyDictionary<T>

A read-only object containing elements of type T, keyed by string.

function winner(scores: ReadonlyDictionary<number>): string {
    let winner = "";
    let highScore = 0;

    for (const name of Object.keys(scores)) {
        if (scores[name] > highScore) {
            highScore = scores[name];
            winner = name;
        }
    }

    return name;
}

ReadonlyDictionary<TValue, TKey>

A read-only object containing elements of type TValue, keyed by TKey.

const amelia = Symbol();
const riley = Symbol();
const april = Symbol();
const xander = Symbol();

type Participant = typeof amelia | typeof riley | typeof april | typeof xander;

function winner(scores: ReadonlyDictionary<number, Participant>): Participant | null {
    let winner: Participant | null = null;
    let highScore = 0;
    
    for (const participant of [amelia, riley, april, xander]) {
        if (scores[participant] > highScore) {
            highScore = scores[participant];
            winner = participant;
        }
    }
    
    return winner;
}

NumberMap<T>

An object containing elements of type T, keyed by number.

ReadonlyNumberMap<T>

A read-only object containing elements of type T, keyed by number.

Copyright

See LICENSE.md.

softwareventures/dictionary-types