Evolution of Web Development Techniques
In the past, frames were a popular choice for web developers, but over time they have lost favor due to various reasons. An article from 2006 discussing this shift can be found here.
It seems that avoiding frames is now the preferred approach in modern web development :)
Choosing Server-Side Includes Over JavaScript
Server-Side Includes (SSI) or other server-based "include" methods are now favored over relying solely on JavaScript. While not a traditional HTML/JS/CSS solution, utilizing SSI offers benefits in certain scenarios.
An example of an SSI statement format is as follows:
<!--#include virtual="../quote.txt" -->
To explore more about SSI, you can visit this link.
Many responses on platforms like Stack Overflow also advocate for using server-side includes. Examples of such discussions can be found here, here, and here.
Note that while some recommend JavaScript solutions, there's a clear preference towards server-side techniques in the end.
Compiling HTML Code for Efficiency
In my experience, when creating a website using only HTML/CSS/JS, I prefer to modularize and "compile" the code before deployment.
This method, though requiring extra work upfront, results in clean and optimized code for deployment. By indicating what content needs inclusion and where, the compiled files contain pure HTML/CSS/JS ready for site hosting.
The use of SASS with Ruby on Rails for compilation is common practice. While specific references elude me currently, I will update my answer once I locate them again.