A class modelled from the Completer in dart, that has promise functionality but also allows external resolution and rejection without the need for scoping

completer.ts

/*
 * completer -
 *
 * the definition of this class mimics the functionality of the completer class that we have defined in the dart
 * packages that lets you deal with unscoped promises instances that can be rejected and resolved in any part of the
 * application so long as you are able to pass the reference to the context properly
 * */

type Resolvable<T> = T | PromiseLike<T>;

export class Completer<T> {
    public promise: Promise<T>;

    // we have to type assert here
    public resolve!: (value: Resolvable<T>) => void;
    public reject!: (reason?: any) => void;

    constructor(options?: { timeout?: number; error?: Error }) {
        this.promise = new Promise((resolve, reject) => {
            this.resolve = resolve;
            this.reject = reject;
        });
        if (options) {
            if (options.timeout) {
                setTimeout(() => {
                    if (options.error) {
                        return this.reject(options.error);
                    }

                    return this.reject(new Error('Completer timeout error'));
                }, options.timeout);
            }
        }
    }
}