In this chapter, we divided feature sets into five separate frames in order to represent five different levels of feature progressions. The last two frames may only work in a WebKit-enabled browser with the most edge features under the hood such as Google Chrome 20 and above, but they should really drive home the idea of building for features that aren't available across the board just yet, but most certainly will be some day. We also showed that there are limits. The last two frames use features that may pass all available tests, but that have implementations that may not work for a specific use case just yet. Also, we had a bit of fun and made it rain features.

We have now managed to illustrate how a singular experience can be enhanced by progression into the upper atmosphere of browser features. I hope that by now you are well aware of the many ways in which the features can be tested for and used in a browser, how fallbacks and progressions can be put into practice, and that your mind is swirling with all sorts of new ideas to put into practice. In the next chapter, we will cover a few more in-depth topics within the library itself, as well as some additional resources.