Bacon.fromBifurcatedCallback

fromBifurcatedCallback.js

/**
 * Similar to Bacon.fromNodeCallback except instead of a single callback,
 * the value and error result are split to two different callbacks.
 * Works for the form method(...args, successCallback, errorCallback);
 * This style of API is used by https://developer.mozilla.org/en-US/docs/Web/API/Navigator/getUserMedia
 */
Bacon.fromBifurcatedCallback = function(method, ...args) {
    return Bacon.fromBinder(sink => {
        args.push(res => {
            sink(res);
            sink(new Bacon.End());
        });
        args.push(err => sink(new Bacon.Error(err)));
        method.apply(undefined, args);
    });
};


// Example using navigator.getUserMedia
var stream = Bacon.fromBifurcatedCallback(navigator.getUserMedia.bind(navigator), {video: true})
stream.onValue(stream => document.querySelector('video').src = window.URL.createObjectURL(stream));
stream.onError(err => console.error('Error getting stream, maybe the user denied permissions.'));