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Dedupe racing promises by arguments
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| export class PromiseCacher<T extends (...args: any[]) => Promise<any>> { | |
| private cache: Map<string, Promise<any>> = new Map(); | |
| private fn: T; | |
| constructor(fn: T) { | |
| this.fn = fn; | |
| } | |
| execute(...args: Parameters<T>): ReturnType<T> { | |
| const key = JSON.stringify(args); | |
| if (this.cache.has(key)) { | |
| return this.cache.get(key) as ReturnType<T>; | |
| } | |
| const promise = this.fn(...args); | |
| this.cache.set(key, promise); | |
| promise.finally(() => { | |
| this.cache.delete(key); | |
| }); | |
| return promise as ReturnType<T>; | |
| } | |
| } | |
| // example | |
| const fetchPromiseCache = new PromiseCacher(async function fetcher(src: string) { | |
| return await fetch(src); | |
| }); | |
| const [a, b] = await Promise.all([fetchPromiseCache.execute('/hello'), fetchPromiseCache.execute('/hello')]); | |
| console.log(a === b); // true | |
| const [a2, b2] = await Promise.all([fetch('/hello'), fetch('/hello')]); | |
| console.log(a2 === b2); // false |
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