Naïve Observable implementation

SimpleObservable.ts

// 1. une source de données

class DataSource {
    ondata: (data: number) => void = () => { };
    interval: number;

    constructor() {
        let i = 0;
        this.interval = setInterval(() => this.emit(++i), 1000);
    }

    emit(i: number) {
        this.ondata(Math.floor(Math.random() * 100));
        if (i === 5) this.destroy();
    }

    destroy() {
        clearInterval(this.interval);
    }
}


// 2. Observer

interface BasicObserver {
    next: (value: any) => void;
}

// 3. Observable

class SimpleObservable {
    constructor(private onsubscribe: (obs: BasicObserver) => void) { }

    subscribe(obs: BasicObserver) {
        this.onsubscribe(obs);
    }

    map(cb: (data: any) => any) {
        const o$ = new SimpleObservable((obs: BasicObserver) => {
            this.subscribe({
                next: v => obs.next(cb(v))
            });
        });
        return o$;
    }

    filter(cb: (data: any) => any) {
        const o$ = new SimpleObservable((obs: BasicObserver) => {
            this.subscribe({
                next: v => {
                    if (cb(v)) obs.next(v);
                }
            });
        });
        return o$;
    }

    tap(cb: (data: any) => any) {
        const o$ = new SimpleObservable((obs: BasicObserver) => {
            this.subscribe({
                next: v => {
                    cb(v);
                    obs.next(v);
                }
            });
        });
        return o$;
    }
}

// 4. Un Observable de DataSource

class DataObservable extends SimpleObservable {
    constructor() {
        super((obs: BasicObserver) => {
            const source = new DataSource();
            source.ondata = obs.next;
        });
    }
}

// 5. testons ça

const o$ = new DataObservable()
    .tap(x => { console.log('tap ', x); })
    .filter(x => x > 50)
    .map(x => `yeah ${ x }`);

o$.subscribe({
    next: (i) => { console.log('observer 1', i); }
});

class MyArray extends Array {
  hello() {
    console.log('hello')
  }
}

const myArray = new MyArray()
const newArray = myArray.map(() => {})

newArray.hello()

// 1. une source de données

class DataSource {
    ondata: (data: number) => void = () => { };
    interval: number;

    constructor() {
        let i = 0;
        this.interval = setInterval(() => this.emit(++i), 1000);
    }

    emit(i: number) {
        this.ondata(Math.floor(Math.random() * 100));
        if (i === 5) this.destroy();
    }

    destroy() {
        clearInterval(this.interval);
    }
}


// 2. Observer

interface BasicObserver {
    next: (value: any) => void;
}

// 3. Observable

class SimpleObservable {
    constructor(private onsubscribe: (obs: BasicObserver) => void) { }

    subscribe(obs: BasicObserver) {
        this.onsubscribe(obs);
    }

    map(cb: (data: any) => any) {
        const o$ = new (<any>this.constructor)((obs: BasicObserver) => {
            this.subscribe({
                next: v => obs.next(cb(v))
            });
        });
        return o$;
    }

    filter(cb: (data: any) => any) {
        const o$ = new (<any>this.constructor)((obs: BasicObserver) => {
            this.subscribe({
                next: v => {
                    if (cb(v)) obs.next(v);
                }
            });
        });
        return o$;
    }

    tap(cb: (data: any) => any) {
        const o$ = new (<any>this.constructor)((obs: BasicObserver) => {
            this.subscribe({
                next: v => {
                    cb(v);
                    obs.next(v);
                }
            });
        });
        return o$;
    }
}

// 4. Un Observable de DataSource

class DataObservable extends SimpleObservable {
    constructor() {
        super((obs: BasicObserver) => {
            const source = new DataSource();
            source.ondata = obs.next;
        });
    }
    hello() {
        console.log('hello')
    }
}

// 5. testons ça

const o$ = new DataObservable()
    .tap(x => { console.log('tap ', x); })
    .filter(x => x > 50)
    .map(x => `yeah ${ x }`);

o$.subscribe({
    next: (i) => { console.log('observer 1', i); }
});

o$.hello();
console.log(o$ instanceof SimpleObservable)
console.log(o$ instanceof DataObservable)