Undetectable features
When there is not sufficient confidence that a feature exists or not, a feature is said to be undetectable. Not everything can be detected by Modernizr because of its limitations or yet to be developed or are partially supported. It is said to be relied on other ways to detect these features. One of these ways is browser detection, which we discussed in the previous section.
Undetectable features are classified into several categories such as HTML5 features that are related to audio/video, networking, typography, events, CSS, and IE Edge. The features mentioned in these categories are found to be undetectable by Modernizr. This list is maintained by Modernizr in their wiki and can be found here at GitHub https://github.com/Modernizr/Modernizr/wiki/Undetectables().
Let's take an example of using @font-face. We are using raleway fonts available at https://github.com/theleagueof/raleway. If you see, all versions of IE will add the fontface CSS class to HTML element, but...
