MediaWiki:Common.js

/* Any JavaScript here will be loaded for all users on every page load. */
$(function() {
    var shortdesc = $('div.shortdescription').text().trim();

    if (shortdesc.length > 0) {
        // SHORTDESC exists: replace the old meta description
        $('meta[name="description"]').remove();

        $('<meta>', {
            name: 'description',
            content: shortdesc
        }).appendTo('head');
    } else {
        // No SHORTDESC: delete any description tag
        $('meta[name="description"]').remove();
    }
});