Build Reactive Websites with RxJS

Loading with Progress Bar

That was the theory—now to build something practical. If you’ve ever implemented a loading bar that pulled together many different bits, you know just how irritating it can be to wrangle all those requests together. Common pre-observable asynchronous patterns plan for only one listener for each event. This results in ridiculous loading bar hacks, like adding a function call to every load event or monkey patching XMLHttpRequest. Using RxJS, our software never leaves our users waiting at 99% (not that I’m bitter).

In the following example, the progress bar represents mutiple requests. It’s also possible to use the same ...