You can also copy and paste it into the browser console, but it is more tedious, so I recommend using a userscript manager to load the script.
I personally have been using Tampermonkey: https://www.tampermonkey.net/

• copy-no-formatting.js - Copy text without formatting
  • I have this enabled everywhere, I rarely want to copy text and retain it's formatting.
• copy-no-format-no-nl.js - Copy text without formatting or newlines
  • This was once useful to me when copying addresses that were on two lines.

• instructure-canvas-open-iframe-in-new-tab.js - Will append a link to open an iframe (useful for embeded videos) in a new tab.

• gmail-get-most-sender.js - Will console.log a list of all senders with more than or equal to 'minSenders' on gmail.

• indeed-jobs-hide.js - Hide Applied, Archived, Interviewing jobs when looking through indeed jobs.

• udemy-show-progress-in-title.js - Will show the progress of the current course in the title of the page and after 'Your progress