73 lines
1.9 KiB
TypeScript
73 lines
1.9 KiB
TypeScript
export type ProgressCallback = (progress: number) => any;
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/**
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* A promise that fires the `onProgress` callback on incremental progress
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*
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* @example
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* ```js
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* const promise = new Promise((resolve, reject, progress) => {
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* const max = 10;
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* for(let i = 0; i < max; i++) progress(i / max);
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* resolve(1);
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* });
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*
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* console.log(promise.progress);
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*
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* promise.onProgress(console.log)
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* .then(console.log)
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* .catch(console.error)
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* .finally(...);
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*
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* ```
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*/
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export class PromiseProgress<T> extends Promise<T> {
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private listeners: ProgressCallback[] = [];
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private _progress = 0;
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get progress() { return this._progress; }
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set progress(p: number) {
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if(p == this._progress) return;
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this._progress = p;
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this.listeners.forEach(l => l(p));
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}
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constructor(executor: (resolve: (value: T) => any, reject: (reason: any) => void, progress: (progress: number) => any) => void) {
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super((resolve, reject) => executor(
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(value: T) => resolve(value),
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(reason: any) => reject(reason),
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(progress: number) => this.progress = progress,
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));
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}
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static from<T>(promise: Promise<T>): PromiseProgress<T> {
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if(promise instanceof PromiseProgress) return promise;
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return new PromiseProgress<T>((res, rej) => promise
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.then((...args) => res(...args))
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.catch((...args) => rej(...args)));
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}
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private from(promise: Promise<T>): PromiseProgress<T> {
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const newPromise = PromiseProgress.from(promise);
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this.onProgress(p => newPromise.progress = p);
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return newPromise;
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}
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onProgress(callback: ProgressCallback) {
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this.listeners.push(callback);
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return this;
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}
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then(res?: (v: T) => any, rej?: (err: any) => any): PromiseProgress<any> {
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const resp = super.then(res, rej);
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return this.from(resp);
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}
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catch(rej?: (err: any) => any): PromiseProgress<any> {
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return this.from(super.catch(rej));
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}
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finally(res?: () => any): PromiseProgress<any> {
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return this.from(super.finally(res));
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}
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}
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