smartpromise/ts/index.ts
2019-09-11 15:37:17 +02:00

80 lines
1.8 KiB
TypeScript

export interface IResolve<T> {
(value?: T | Promise<T>): void;
}
export interface IReject {
(reason?: any): void;
}
export type TDeferredStatus = 'pending' | 'fulfilled' | 'rejected';
export class Deferred<T> {
public promise: Promise<T>;
public resolve: IResolve<T>;
public reject: IReject;
public status: TDeferredStatus;
public startedAt: number;
public stoppedAt: number;
public get duration(): number {
if (this.stoppedAt) {
return this.stoppedAt - this.startedAt;
} else {
return Date.now() - this.startedAt;
}
}
constructor() {
this.promise = new Promise<T>((resolve, reject) => {
this.resolve = (valueArg: T | PromiseLike<T>) => {
this.status = 'fulfilled';
this.stoppedAt = Date.now();
resolve(valueArg);
};
this.reject = (reason: any) => {
this.status = 'rejected';
this.stoppedAt = Date.now();
reject(reason);
};
this.startedAt = Date.now();
this.status = 'pending';
});
}
}
export let defer = <T>() => {
return new Deferred<T>();
};
/**
* Creates a new resolved promise for the provided value.
*/
export let resolvedPromise = <T>(value?: T): Promise<T> => {
return Promise.resolve(value);
};
/**
* Creates a new rejected promise for the provided reason.
*/
export let rejectedPromise = err => {
return Promise.reject(err);
};
interface IAsyncFunction<T> {
(someArg: T): Promise<T>;
}
export let map = async <T>(inputArg: T[], functionArg: IAsyncFunction<T>) => {
let promiseArray: Promise<any>[] = [];
let resultArray = [];
for (let item of inputArg) {
let promise: Promise<any> = functionArg(item);
promiseArray.push(promise);
promise.then(x => {
resultArray.push(x);
});
}
await Promise.all(promiseArray);
return resultArray;
};