Mike Turley for CSS-Tricks:

JavaScript developers have realized that by defining a page’s structure in JavaScript instead of in HTML (using frameworks such as React), they can simplify the development and maintenance of user interaction code that is otherwise much more complex to build. Of course, when you tell someone that the HTML they wrote needs to be chopped up and mixed in with JavaScript they don’t know anything about, they can (understandably) become frustrated and start asking what the heck we’re getting out of this.

I get this question occasionally and I often have trouble answering it. All of the materials I’ve found on this topic are written for an audience that is already familiar with JavaScript — which is not terribly useful to those who focus on HTML and CSS. But this HTML-in-JS pattern (or something else that provides the same benefits) will likely be around for a while, so I think it’s an important thing that everyone involved in web development should understand.