MediaWiki:Common.js

mw.loader.using('mediawiki.util', function () {
  $(function(){
    // Get the list of categories assigned to this page
    var cats = mw.config.get('wgCategories') || [];
    // Specify the category you want to target
    var targetCat = 'InternationalisationForms';

    // Only proceed if the page is in that category
    if ( cats.indexOf(targetCat) !== -1 ) {
      // Create and style the button-like link
     var $pdfLink = $('<a>')
        .text('📄 Export this page to PDF')
        .attr('href','#')
        .css({
           display: 'inline-block',
        padding: '0.39em 0.77em',
        'font-size': '0.82em',
        'background-color': '#19529E',
        color: '#fff',
        'text-decoration': 'none',
        'border-radius': '3px',
        margin: '0.39em'
        })
        .click(function(e){
          e.preventDefault();
          window.print();
        })
        $('#content').before(
        $('<div>')
        .attr('id', 'export-to-pdf-container')
        .css({ 'text-align': 'right', padding: '0.5em' })
        .append($pdfLink)
    );
    }
  });
});