You’ll find technical information about JavaScript (user scripts) here:
Wikipedia:WikiProject User scripts (shortcut: WP:US)
Help:User style (shortcut: H:US)
User scripts are scattered throughout Wikipedia. You may find one just because someone mentioned it, or because you came across it in the index (shortcut: WP:EIW). The largest collection of scripts (or links to scripts) is at Wikipedia:WikiProject User scripts/Scripts (shortcut: WP:JS). Other places to check are:
User:Voice of All/UsefulJS
User:GeorgeMoney/UserScripts
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