This is why I prefer userscripts instead of extensions for simple things like this. Usually, they can be achieved with a single or few lines of code; even thoug

This is why I prefer userscripts instead of extensions for simple things like this. Usually, they can be achieved with a single or few lines of code; even though I am not a programmer (and certainly not a Javascript programmer) I can often write one with a little bit of research. No need to extend the attack surface with yet another extension for every little thing. You might be able to inspect the code of an extension, but it is less straightforward and easy compared to a simple userscript. Plus, with a userscript, there is no risk of the extension author turning malicious and updating it with malware, even if it was clean at one point. My rule of thumb is using userscripts to modify websites' behavior, and using extensions to modify the browser's behavior. (At least that is the case for Firefox 56: Firefox Quantum and Chrome limits extensions from modifying the browser much; often they are little more than glorified userscripts.)