Native Await New

AwaitNew.ts

'use strict';

class MyPromise<T> extends Promise<T> {
    constructor(handler: (
        resolve: (value: T) => unknown,
        reject: () => unknown) => void
    ) {
        super(handler);
    }
}

const myItem = new MyPromise((resolve, reject) => {
    resolve(123);
});

console.log('myItem instanceof Promise', myItem instanceof Promise);

(async () => {
    console.log(await myItem);
    console.log(await new MyPromise((resolve) => {
        resolve(321);
    }));
})();

NativeAwaitNew.js

'use strict';

class MyPromise extends Promise {

    #_resolved = false;
    #_rejected = false;
    #_happyValue
    #_unhappyValue

    constructor(handler) {
        console.log('my promise call 1 : ', new.target);

        let resolve, reject;
        super((_resolve, _reject) => {
            resolve = _resolve;
            reject = _reject;
        });

        const self = this;

        handler((happyValue) => {
            if (self.#_resolved) {
                console.log(' thenable happy value : ', self.#_happyValue, happyValue);
                resolve(self.#_happyValue);
                return;
            }
            self.#_happyValue = happyValue;
            console.log(' happy value : ', self.#_happyValue);
            resolve(self.#_happyValue);
            self.#_resolved = true;
        }, (unhappyValue) => {
            if (self.#_rejected) {
                console.log(' thenable unhappy value : ', self.#_unhappyValue, unhappyValue);
                reject(self._unhappyValue);
                return;
            }
            self.#_unhappyValue = _unhappyValue;
            console.log(' unhappy value : ', self.#_unhappyValue);
            reject(self.#_unhappyValue);
            self.#_rejected = true;
        });

        console.log('my promise call 2');
    }
    get self() {
        return this;
    }

    // get then() {
    //     const self = this;
    //     console.log('Then Getter Call');
    //     return function (cb) {
    //         console.log('Then Resulter Call');
    //         if (self.#_thenAlreadyCalled) {
    //             const answer = cb(self.#_happyValue);
    //             self.#_happyValue = answer;
    //             return self;
    //         }
    //         self.#_thenAlreadyCalled = true;
    //         const answer = cb(self.#_happyValue);
    //         self.#_happyValue = answer;
    //         return self;
    //     }
    // }

    // [Symbol.species]() {
    //     return Promise;
    // }
};


(async () => {

    console.log('\n --- ↓↓↓ --- 321 starts here --- ↓↓↓ --- \n')
    console.log(' awaited result : ', await new MyPromise((resolve) => {
        setTimeout(() => {
            const value = 321;
            resolve(value);
        }, 1000);
    }));

    console.log('\n --- ↓↓↓ --- chained starts here --- ↓↓↓ --- \n')
    console.log(' awaited result : ', await new MyPromise((resolve) => {
        setTimeout(() => {
            const value = 'chained 1';
            resolve(value);
        }, 1000);
    }).then((value) => {
        console.log(value);
        return 'chained 2'
    }));

    console.log('\n --- ↓↓↓ --- 123 starts here --- ↓↓↓ --- \n')

    console.time(' spent time ');

    const instance = new MyPromise((resolve, reject) => {
        console.log('native promise call');
        setTimeout(() => {
            console.log('pre resolve call');
            resolve(123);
            console.log('post resolve call');
        }, 1000);
    });

    console.log('\n');
    console.log(' instanceof Promise   : ', instance instanceof Promise);
    console.log(' instanceof MyPromise : ', instance instanceof MyPromise);
    console.log(' instance .self       : ', instance.self);
    console.log('\n');
    
    
    instance
    .then((result) => {
            console.log('\n');
            console.log(' then result          : ', result);
            console.log(' then this            : ', Object.getPrototypeOf(this));
            console.log(' instance       .self : ', instance.self);
            console.log('\n');
            console.timeEnd(' spent time ');
            console.log('\n');
            return 345;
        })
        .then((result) => {
            console.log('see additional .constructor invocation ', result);
            console.log('\n');
            return 567;
        })
        .then((result) => {
            console.log('see additional .constructor invocation ', result);
            console.log('\n');
            return 789;
        });
})();