callbag-to-obs v1.0.0

/**

• callbag-to-obs

• ---

• Convert a listenable callbag source to an observable (or subscribable).
• The Observable is an object following the ECMAScript Observable proposal
• https://github.com/tc39/proposal-observable and at a minimum has the method
• "subscribe(observer)" attached to it.
• npm install callbag-to-obs
• Example:

• const {pipe, interval, take, filter, map} = require('callbag-basics');

• const toObservable = require('callbag-to-obs');

• const observable = pipe(

•   interval(1000), // 0,1,2,3,4,5,6,7,...

•   take(5), // 0,1,2,3,4

•   filter(x => x !== 0), // 1,2,3,4

•   map(x => x * 10), // 10,20,30,40

•   toObservable

• );

• observable.subscribe({

•   next: x => console.log(x)

• });

  */

const $$observable = require('symbol-observable').default;

function normalize(observer) { if (!observer.start) observer.start = () => { }; if (!observer.next) observer.next = () => { }; if (!observer.error) observer.error = () => { }; if (!observer.complete) observer.complete = () => { }; }

function toObservable(source) { return { subscribe: function subscribe(observer) { normalize(observer); let talkback; const sub = { unsubscribe: function unsubscribe() { if (talkback) talkback(2); }, }; observer.start(sub); try { source(0, (t, d) => { if (t === 0) talkback = d; if (t === 1) observer.next(d); if (t === 2 && d) observer.error(d); else if (t === 2) talkback = void 0, observer.complete(d); }); } catch (err) { observer.error(err); } return sub; },

[$$observable]: function () { return this; },

}; }

module.exports = toObservable;