Manual:$wgResourceModules

Below is an example of how to use this in an extension. You would put this in your extension.json file.

"ResourceModules": {
    "ext.MyExtension": {
        "localBasePath": "modules/ext.MyExtension",
        "remoteExtPath": "MyExtension/modules/ext.MyExtension",
        "styles": [
            "foo.css",
            "bar.css"
        ],
        "packageFiles": [
            "index.js",
            "foo.js"
        ],
        "messages": [
            "myextension-foo-label"
        ],
        "dependencies": [
            "jquery.cookie",
            "mediawiki.util"
        ]
    }
},

See MainConfigSchema::ResourceModules.

See ResourceLoader/Migration guide (developers)#Adding a module to the page :

If you require a list of all registered modules, it is not recommended to call $GLOBALS[ 'wgResourceModules' ] from a skin or extension. The list may not be complete at the time of the request. See ResourceLoader::getModuleNames() instead.

• ResourceLoader
• $wgResourceModules - Register modules that can later be loaded on a page
• $wgResourceModuleSkinStyles - Register skin-provided stylesheets to add to an existing ResourceLoader module
• $wgResourceLoaderDebug - Configure the default debug mode for MediaWiki.
• Internal configuration settings: $wgExtensionAssetsPath , $wgResourceLoaderMaxage
• ResourceLoaderRegisterModules hook
• Developing with ResourceLoader – Learn how to use ResourceLoader in MediaWiki