@mindfulminun/pear@1.5.1
latest
MindfulMinun/pearBenji's personal standard library. Collection of tools for manipulating strings, async iterables, shell scripting, and common data structures.
This package works with Deno, BrowsersIt is unknown whether this package works with Cloudflare Workers, Node.js, Bun
JSR Score
76%
Published
2 months ago (1.5.1)
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165/** * Promise that resolves after timeout, optionally with a value to resolve with. * * @example * // Play hide and seek, count to 100 (seconds) * // Both methods are identical * wait(100e3).then(() => "Ready or not, here I come!").then(seek) * wait(100e3, "Ready or not, here I come!").then(seek) * @since 2020-06-23 */ export function wait(timeout: number): Promise<void> export function wait<T>(timeout: number, resolveWith: T): Promise<T> export function wait<T>(timeout: number, resolveWith?: T): Promise<T | void> { return new Promise(resolve => setTimeout(() => resolve(resolveWith), timeout)) } /** * Helper class to handle events and turn them into async iterables * * ```ts * const stream = new EventStream<MouseEvent>() * * document.body.addEventListener('click', ev => stream.emit(ev)) * wait(10e3).then(() => stream.end()) * * for await (const event of stream) { * alert("Clicked!") * } * ``` * @since 2021-08-07 */ export class EventStream<T> implements AsyncIterable<T> { #done: boolean #events: T[] #resolve: () => void #promise!: Promise<void> constructor() { this.#done = false this.#events = [] this.#resolve = () => { } this.#defer() } #defer() { this.#promise = new Promise(r => this.#resolve = r) } async*[Symbol.asyncIterator](): AsyncGenerator<Awaited<T>, void, undefined> { while (!this.#done) { await this.#promise yield* this.#events this.#events = [] } } /** * Dispatches an event. For-await-of listeners of this class instance will recieve this event. * Note that once an event is emitted, it cannot be cancelled. * @since 2021-08-07 */ emit(event: T) { this.#events.push(event) this.#resolve() this.#defer() } /** * Waits for a specific event to be emitted according to a predicate. * * @example * const stream = new EventStream<MouseEvent>() * // Some events happen... * const click = stream.once(ev => ev.type === 'click') * @since 2021-12-22 */ once(predicate: (value: T) => boolean): Promise<Awaited<T> | undefined> { return once(this, predicate) } /** * Stops the iterator. This terminates for-await-of loops listening for events, * and any newly dispatched events will not be sent to the iterator. * @since 2021-08-07 */ end() { this.#done = true this.#resolve() } /** * Iterate over the event stream, calling a callback for each event. * @author MindfulMinun * @since 2024-06-02 */ each(callback: (value: T) => void): Promise<void> { return each(this, callback) } } /** * Wait for any async iterable to yield a specific value according to a predicate. * * @example * const stream = new EventStream<MouseEvent>() * // Some events happen... * const click = once(stream, ev => ev.type === 'click') * @since 2021-12-22 */ export async function once<T>(source: AsyncIterable<T>, predicate: (value: T) => boolean): Promise<T | undefined> { for await (const value of source) { if (predicate(value)) return value } } /** * Iterate over an async iterable, calling a callback for each value. * * @author MindfulMinun * @since 2024-06-02 */ export async function each<T>(source: AsyncIterable<T>, callback: (value: T) => void) { for await (const value of source) { callback(value) } } /** * A "destructured" Promise, useful for waiting for callbacks. * @example * // When awaited, this function returns a promise that resolves to * // an *OPEN* WebSocket * () => { * const sock = new WebSocket('wss://wss.example.com') * const [p, res, rej] = pinkyPromise<typeof sock>() * sock.onerror = err => rej(err) * sock.onopen = () => res(sock) * return p * } * * @author MindfulMinun * @since 2022-06-05 */ export function pinkyPromise(): [Promise<void>, () => void, (reason?: unknown) => void] export function pinkyPromise<T>(): [Promise<T>, (value: T) => void, (reason?: unknown) => void] export function pinkyPromise<T>(): [ Promise<T | void>, (value?: T | PromiseLike<T>) => void, (reason?: unknown) => void ] { let resolve: (value?: T | PromiseLike<T>) => void let reject: (error: unknown) => void // This works because callbacks to the Promise constructor are called synchronously. const p = new Promise<T | void>((yay, nay) => { resolve = value => yay(value) reject = reason => nay(reason) }) // HACK: This works because callbacks to the Promise constructor are called synchronously. // In other words, they're immediately invoked, so they're available immediately after // the assignment to `p` return [p, resolve!, reject!] }