What type of attack is based on the automated download of malware that takes advantage of a browsers’ ability to download the different files that compose a web page?

There are multiple attacks possible, however you are most likely talking about XSS or Cross Site Scripting.

Explanation:

XSS occurs when one of the externally loaded js files that a website uses is compromised and loaded with malicious code. The malicious code will then run on all of the website's user's browsers.

For example, say that myblog.com has Google Ads and references a GoogleAds.js file from a CDN. If I were to compromise that CDN and upload my own js file, I would now effectively be able to run js code on all of the browsers that pull this file from my CDN, including myblog.com. This would allow me to execute clickjacking attacks, or browser attacks through frameworks like BeEf.

that without the operating systems you would have to control and synchronize computer hardware.