Require this script and you will get variable GMRequireChecker equals to true if loaded. In other cases, variable GMRequireChecker will just not exists.
Ce script ne doit pas être installé directement. C'est une librairie destinée à être incluse dans d'autres scripts avec la méta-directive // @require https://update.greasyfork.org/scripts/429557/951692/GMRequireChecker.js
A simple script to check whether @require works.
if it works, then you can get variable GMRequiredJSLoaded which equals to true. Otherwise, GMRequiredJSLoaded will just not exist.
You can also use this script to check whether your script is running in a non-ScriptManager-environment.