pastebin-stream/src/promise-set-interval.js

'use strict';

const Promise = require("bluebird");
const createEventEmitter = require("create-event-emitter");

const clampZero = require("./clamp-zero");

module.exports = function promiseSetInterval(callback, interval, options = {}) {
	let lastInvocation = Date.now();
	let timeout;

	let emitter = createEventEmitter({
		cancel: function cancelInterval() {
			clearTimeout(timeout);
		}
	});

	function scheduleNext() {
		let delta = Date.now() - lastInvocation;
		let timeout = clampZero(interval - delta);

		scheduleInvocation(timeout);
	}

	function scheduleInvocation(nextTimeout) {
		timeout = setTimeout(() => {
			Promise.try(() => {
				lastInvocation = Date.now();
				return callback();
			}).then(() => {
				scheduleNext();
			}).catch((err) => {
				emitter.emit("error", err);

				if (!options.abortOnError) {
					scheduleNext();
				}
			});
		}, nextTimeout);
	}

	if (options.startImmediately) {
		scheduleInvocation(0);
	} else {
		scheduleNext();
	}

	return emitter;
};