MediaWiki:Common.js

console.log('testme')
mw.loader.using('ext.visualEditor.desktopArticleTarget.init').then(function () {
    mw.hook('ve.activationComplete').add(function () {

        // --- Define the command ---
        function doHighlight(surface) {
            var fragment = surface.getModel().getFragment();
            var selectedText = fragment.getText();
            if (!selectedText) {
                return;
            }

            // Replace selected text with the template call
            fragment.insertContent('{{Highlight|' + selectedText + '|yellow}}');
        }

        var commandName = 'insertHighlight';

        // Register command
        if (!ve.ui.commandRegistry.lookup(commandName)) {
            ve.ui.commandRegistry.register(
                new ve.ui.Command(
                    commandName,
                    'content',
                    'exec',
                    { args: [doHighlight] }
                )
            );
        }

        // --- Define the tool ---
        function HighlightTool(toolGroup, config) {
            ve.ui.Tool.call(this, toolGroup, config);
        }
        OO.inheritClass(HighlightTool, ve.ui.Tool);

        HighlightTool.static.name = 'highlight';
        HighlightTool.static.group = 'insert';   // Puts it into the Insert group
        HighlightTool.static.icon = 'highlight'; // Uses built-in OOUI icon
        HighlightTool.static.title = 'Highlight text';
        HighlightTool.static.commandName = commandName;

        if (!ve.ui.toolFactory.lookup('highlight')) {
            ve.ui.toolFactory.register(HighlightTool);
        }
    });
});