Single-page applications

It's worth discussing exactly what a SPA is. We've touched on this topic before, but let's now take a look at why Angular (and React and Vue, which we'll get to shortly) are popular and compelling to use. Think of a standard, HTML-based website. It probably has a consistent header, footer, and styling. However, a standard website needs to download (or serve from local cache) these assets every time you navigate to a different page (not to mention retrieving the HTML and rerendering it). A SPA eliminates this redundancy by packaging together all of the relevant data into one unified package that's transmitted to the browser. The browser then parses the JavaScript and renders it. The result is a fast, smooth experience that essentially eliminates page load time lag. You've used these already. If you use Gmail or most of the modern online email systems, you may have noticed that the page load time is negligible, or, at worst, has a small...