/* Examples From JavaScript: The Definitive Guide, Fourth Edition Legal matters: these files were created by David Flanagan, and are Copyright (c) 2001 by David Flanagan. You may use, study, modify, and distribute them for any purpose. Please note that these examples are provided "as-is" and come with no warranty of any kind. David Flanagan */ /** * Create a table of contents for this document, and insert the TOC into * the document by replacing the node specified by the replace argument. **/ function maketoc(replace) { // Create a
element that will hold the TOC and add it var table = document.createElement("table"); toc.appendChild(table); // Create a element that holds the rows of the TOC var tbody = document.createElement("tbody"); table.appendChild(tbody); // Initialize an array that keeps track of section numbers var sectionNumbers = [0,0,0,0,0,0]; // Recursively traverse the body of the document, looking for sections // marked with
,
, ... tags, and use them to create the TOC // by adding rows to the table. addSections(document.body, tbody, sectionNumbers); // Finally, insert the TOC into the document by replacing the node // specified by the replace argument with the TOC sub-tree replace.parentNode.replaceChild(toc, replace); // This method recursively traverses the tree rooted at node n, looking // for
through
tags and uses the content of these tags to build // the table of contents by adding rows to the HTML table specified by the // toc argument. It uses the sectionNumbers array to keep track of the // current section number. // This function is defined inside of maketoc() so that it is not // visible from the outside. maketoc() is the only function // exported by this JavaScript module. function addSections(n, toc, sectionNumbers) { // Loop through all the children of n for(var m = n.firstChild; m != null; m = m.nextSibling) { // Check whether m is a heading element. It would be nice if we // could just use (m instanceof HTMLHeadingElement), but this is // not required by the specification and it does not work in IE. // Therefore we've got to check the tagname to see if it is H1-H6. if ((m.nodeType == 1) && /* Node.ELEMENT_NODE */ (m.tagName.length == 2) && (m.tagName.charAt(0) == "H")) { // Figure out what level heading it is var level = parseInt(m.tagName.charAt(1)); if (!isNaN(level) && (level >= 1) && (level <= 6)) { // Increment the section number for this heading level sectionNumbers[level-1]++; // And reset all lower heading level numbers to zero for(var i = level; i < 6; i++) sectionNumbers[i] = 0; // Now combine section numbers for all heading levels // to produce a section number like 2.3.1 var sectionNumber = ""; for(var i = 0; i < level; i++) { sectionNumber += sectionNumbers[i]; if (i < level-1) sectionNumber += "."; } // Create an anchor to mark the beginning of this section. // This will be the target of a link we add to the TOC. var anchor = document.createElement("a"); anchor.setAttribute("name", "SECT"+sectionNumber); // Create a link back to the TOC and make it a // child of the anchor var backlink = document.createElement("a"); backlink.setAttribute("href", "#TOC"); backlink.appendChild(document.createTextNode("Contents")); anchor.appendChild(backlink); // Insert the anchor into the document right before the // section header n.insertBefore(anchor, m); // Now create a link to this section. It will be added // to the TOC below. var link = document.createElement("a"); link.setAttribute("href", "#SECT" + sectionNumber); // Get the heading text using a function defined below var sectionTitle = getTextContent(m); // Use the heading text as the content of the link. link.appendChild(document.createTextNode(sectionTitle)); // Create a new row for the TOC var row = document.createElement("tr"); // Create two columns for the row var col1 = document.createElement("td"); var col2 = document.createElement("td"); // Make the first column right-aligned and put the section // number in it col1.setAttribute("align", "right"); col1.appendChild(document.createTextNode(sectionNumber)); // Put a link to the section in the second column col2.appendChild(link); // Add the columns to the row, and the row to the table row.appendChild(col1); row.appendChild(col2); toc.appendChild(row); // Modify the section header element itself to add // the section number as part of the section title m.insertBefore(document.createTextNode(sectionNumber+": "), m.firstChild); } } else { // Otherwise, this is not a heading element, so recurse addSections(m, toc, sectionNumbers); } } } // This utility function traverses the node n, returning the content of // all text nodes found, and discarding any HTML tags. This is also // defined as a nested function so that it is private to this module. function getTextContent(n) { var s = ''; var children = n.childNodes; for(var i = 0; i < children.length; i++) { var child = children[i]; if (child.nodeType == 3 /*Node.TEXT_NODE*/) s += child.data; else s += getTextContent(child); } return s; } }