The HTML is parsed, JavaScript is executed, and the result is the DOM. The content of a web page is not (just) source code, it’s the DOM. This makes it pretty important.

However, the JavaScript in the .html has access to the HTML elements defined in the .cshtml page. The primary restriction on that JavaScript code is that it should not change the structure of the page ...

"For fun," he built a complete PC emulator in JavaScript, and then used it to run a fully functioning version of Linux in a web browser. How did it turn out?