colorify/app/js/workers/last-in-worker.js

a collection of color tools

module.exports = function (InputWorker, handler) {
	return (function () {
		const api = {};
		const worker = new InputWorker();
		let isExecuting = false;
		let pendingJob;
		let numPosts = 0;

		// make sure handler is a function
		if (typeof handler !== 'function') {
			handler = function () {};
		}

		// worker.postMessage wrapper for debugging
		const postMessage = function (data) {
			worker.postMessage(data);
			numPosts++;
		};

		// send pending job if needed, and call handler
		worker.onmessage = function (event) {
			if (pendingJob) {
				postMessage(pendingJob);
			} else {
				isExecuting = false;
			}
			pendingJob = null;
			if (event.data) {
				handler(event.data);
			}
		};

		// execute immediately, or store as a pending job
		api.exec = function () {
			const args = Array.prototype.slice.call(arguments);
			if (isExecuting) {
				pendingJob = args;
			} else {
				isExecuting = true;
				postMessage(args);
			}
		};

		// terminate our worker
		api.terminate = function () {
			return worker.terminate();
		};

		return api;
	}());
};