| 123456789101112131415161718192021222324 | $(document).ready(function () {  'use strict';  // Use attr() to add an id, rel, and title.  $('div.chapter a[href*="wikipedia"]').attr({    rel: 'external',    title: function () {      return 'Learn more about ' + $(this).text() + ' at Wikipedia.';    },    id: function (index, oldValue) {      return 'wikilink-' + index;    }  });  // Add "back to top" links.  $('<a href="#top">back to top</a>').insertAfter('div.chapter p');  $('<a id="top"></a>').prependTo('body');  // insertBefore <elem> prependTo <children /> appendTo </elem> insertAfter  // Create footnotes.  $('span.footnote').insertBefore('#footer');  // This works just as well, in spite of what the book says.  // $('span.footnote').insertAfter('div.chapter');});
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