node-promise-delay-every/index.js

"use strict";

module.exports = function promiseDelayEvery(delay) {
	let lastScheduledEmit = 0;

	return function delayer() {
		return new Promise((resolve, _reject) => {
			let targetTime = lastScheduledEmit + delay;
			let currentTime = Date.now();

			if (currentTime >= targetTime) {
				lastScheduledEmit = currentTime;
				resolve();
			} else {
				lastScheduledEmit = targetTime;

				setTimeout(() => {
					resolve();
				}, targetTime - currentTime);
			}
		});
	}
};