MediaWiki:Common.js/sources.js

/* Any JavaScript here will be loaded for all users on the upload page. */
//<source lang="javascript">

var template = "{" + "{Image summary\n| summary = \n| artist  = \n| source  = \n}}";

if (window.jQuery) {
    jQuery(document).ready(function() {
        if (jQuery('#wpUploadDescription').text() == '') {
            jQuery('#wpUploadDescription').text(template);
        }

        $('#mw-upload-form').submit(function() {
            if (jQuery('#wpUploadDescription').text().toLowerCase().indexOf('image summary') == -1) {
                alert('Please use the image template summary.');
                return false;
            }
            else return true;
        });
    });
}

//</source>