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URL: https://www.javascriptbank.com/javascript-content-auto-indexing-using-dom.html
On the web pages with a lot of text content such as technical documents, novels, text stories, reportages, etc; usually we have to create the bookrmarks (anchor links) manuallly. Now these time-consuming jobs like that will be not available if the web pages use this JavaScript code example; this JavaScript code makes it easy for people to jump to the section they want to read by making a table of contents using the h1 to h6 tags automatically. Now it's time to create content only for content publishers!
Full version: jsB@nk » Menu » Navigation » JavaScript Content Auto-Indexing using DOM
URL: https://www.javascriptbank.com/javascript-content-auto-indexing-using-dom.html
<style type="text/css">.hidden { visibility: hidden;}</style><script type="text/javascript">// Created by: Stuart Langridge | http://www.kryogenix.org/ | Licensed under: MIT License// This script downloaded from www.JavaScriptBank.com/*Generate a table of contents, based on headings in the page.To place the TOC on the page, add<div id="generated-toc"></div>to the page where you want the TOC to appear. If this elementis not present, the TOC will not appear.The TOC defaults to displaying all headings that are contained withinthe same element as it itself is contained in (or all headings on thepage if you did not provide a generated-toc container). To override this,provide a "highest heading" value by adding class="generate_from_h3"(or h2, h4, etc) to the container. (If unspecified, this will display allheadings, as if class="generate_from_h1" was specified.)The TOC defaults to operating only on headings contained within the sameelement as it itself, i.e., in a page like this:<div> <div> <div id="generated-toc"></div> <h1>foo</h1> <h2>bar</h2> </div> <h1>quux</h1></div>The "quux" heading will not appear in the TOC. To override this,add class="generate_for_page" to the container, which will processall headings on the page wheresoever they may be.*/generated_toc = { generate: function() { // Identify our TOC element, and what it applies to generate_from = '0'; generate_for = 'unset'; tocparent = document.getElementById('generated-toc'); if (tocparent) { // there is a div class="generated-toc" in the document // dictating where the TOC should appear classes = tocparent.className.split(/\s+/); for (var i=0; i<classes.length; i++) { // if it specifies which heading level to generate from, // or what level to generate for, save these specifications if (classes[i].match(/^generate_from_h[1-6]$/)) { generate_from = classes[i].substr(classes[i].length-1,1); } else if (classes[i].match(/^generate_for_[a-z]+$/)) { generate_for = classes[i].match(/^generate_for_([a-z])+$/)[1]; } } } else { // They didn't specify a TOC element; exit return; } // set top_node to be the element in the document under which // we'll be analysing headings if (generate_for == 'page') { top_node = document.getElementsByTagName('body'); } else { // i.e., explicitly set to "parent", left blank (so "unset"), // or some invalid value top_node = tocparent.parentNode; } // If there isn't a specified header level to generate from, work // out what the first header level inside top_node is // and make that the specified header level if (generate_from == 0) { first_header_found = generated_toc.findFirstHeader(top_node); if (!first_header_found) { // there were no headers at all inside top_node! return; } else { generate_from = first_header_found.toLowerCase().substr(1); } } // add all levels of heading we're paying attention to to the // headings_to_treat dictionary, ready to be filled in later headings_to_treat = {"h6":''}; for (var i=5; i>= parseInt(generate_from); i--) { headings_to_treat["h" + i] = ''; } // get headings. We can't say // getElementsByTagName("h1" or "h2" or "h3"), etc, so get all // elements and filter them ourselves // need to use .all here because IE doesn't support gEBTN('*') nodes = top_node.all ? top_node.all : top_node.getElementsByTagName('*'); // put all the headings we care about in headings headings = []; for (var i=0; i<nodes.length;i++) { if (nodes[i].nodeName.toLowerCase() in headings_to_treat) { // if heading has class no-TOC, skip it if ((' ' + nodes[i].className + ' ').indexOf('no-TOC') != -1) { continue; } headings.push(nodes[i]); } } // make the basic elements of the TOC itself, ready to fill into // first, check if there's a cookie defined to save the state as open status = generated_toc.readCookie("generated_toc_display"); if (status && status == "open") { display_initially = "block"; toggle_initially = "Hide table of contents"; } else { display_initially = "none"; toggle_initially = "Show table of contents"; } cur_head_lvl = "h" + generate_from; cur_list_el = document.createElement('ul'); cur_list_el.style.display = display_initially; p = document.createElement('p'); span = document.createElement('span'); span.className = 'hidden'; a = document.createElement('a'); a.href = '#aftertoc'; a.appendChild(document.createTextNode('skip table of contents')); span.appendChild(a); p.appendChild(span); tocparent.appendChild(p); p = document.createElement('p'); p.id = 'toggle-container'; a = document.createElement('a'); a.id = 'generated_toc_d_toggle'; a.appendChild(document.createTextNode(toggle_initially)); p.appendChild(a); a.onclick = generated_toc.wrapOpenClose(a,cur_list_el); a.href = '#'; tocparent.appendChild(p); tocparent.appendChild(cur_list_el); // now walk through our saved heading nodes for (var i=0; i<headings.length; i++) { this_head_el = headings[i]; this_head_lvl = headings[i].nodeName.toLowerCase(); if (!this_head_el.id) { // if heading doesn't have an ID, give it one this_head_el.id = 'heading_toc_j_' + i; this_head_el.setAttribute('tabindex','-1'); } while(this_head_lvl > cur_head_lvl) { // this heading is at a lower level than the last one; // create additional nested lists to put it at the right level // get the *last* LI in the current list, and add our new UL to it var last_listitem_el = null; for (var j=0; j<cur_list_el.childNodes.length; j++) { if (cur_list_el.childNodes[j].nodeName.toLowerCase() == 'li') { last_listitem_el = cur_list_el.childNodes[j]; } } if (!last_listitem_el) { // there aren't any LIs, so create a new one to add the UL to last_listitem_el = document.createElement('li'); } new_list_el = document.createElement('ul'); last_listitem_el.appendChild(new_list_el); cur_list_el.appendChild(last_listitem_el); cur_list_el = new_list_el; cur_head_lvl = 'h' + (parseInt(cur_head_lvl.substr(1,1)) + 1); } while (this_head_lvl < cur_head_lvl) { // this heading is at a higher level than the last one; // go back up the TOC to put it at the right level cur_list_el = cur_list_el.parentNode.parentNode; cur_head_lvl = 'h' + (parseInt(cur_head_lvl.substr(1,1)) - 1); } // create a link to this heading, and add it to the TOC li = document.createElement('li'); a = document.createElement('a'); a.href = '#' + this_head_el.id; a.appendChild(document.createTextNode(generated_toc.innerText(this_head_el))); li.appendChild(a); cur_list_el.appendChild(li); } // add an aftertoc paragraph as destination for the skip-toc link p = document.createElement('p'); p.id = 'aftertoc'; tocparent.appendChild(p); // go through the TOC and find all LIs that are "empty", i.e., contain // only ULs and no links, and give them class="missing" var alllis = tocparent.getElementsByTagName("li"); for (var i=0; i<alllis.length; i++) { var foundlink = false; for (var j=0; j<alllis[i].childNodes.length; j++) { if (alllis[i].childNodes[j].nodeName.toLowerCase() == 'a') { foundlink = true; } } if (!foundlink) { alllis[i].className = "missing"; } else { alllis[i].className = "notmissing"; } } }, wrapOpenClose: function(a, cur_list_el) { // we return a function here so that it acts as a closure; // in essence the inner function, which is the event handler // for clicking on the toggle-toc link, remembers the a and cur_list_el // elements as they are when they're passed in to it. // This is an explicit function rather than an anonymous function // defined where it's called so it's easier to understand. return function(e) { d = cur_list_el.style.display; a.firstChild.nodeValue = (d == 'block' ? 'Show' : 'Hide') + ' table of contents'; a.className = (d == 'block' ? 'toggle-closed' : 'toggle-open'); cur_list_el.style.display = d == 'block' ? 'none' : 'block'; // set a cookie to "open" or "closed" to save the state of the TOC if (cur_list_el.style.display == "block") { generated_toc.createCookie("generated_toc_display","open",21); } else { generated_toc.createCookie("generated_toc_display","closed",21); } if (window.event) { window.event.returnValue = false; window.event.cancelBubble = true; } else { e.preventDefault(); e.stopPropagation(); } } }, /* cookie handling: http://www.quirksmode.org/js/cookies.html */ createCookie: function(name,value,days) { if (days) { var date = new Date(); date.setTime(date.getTime()+(days*24*60*60*1000)); var expires = "; expires="+date.toGMTString(); } else var expires = ""; document.cookie = name+"="+value+expires+"; path=/"; }, readCookie: function(name) { var nameEQ = name + "="; var ca = document.cookie.split(';'); for(var i=0;i < ca.length;i++) { var c = ca[i]; while (c.charAt(0)==' ') c = c.substring(1,c.length); if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length); } return null; }, eraseCookie: function(name) { createCookie(name,"",-1); }, innerText: function(el) { return (typeof(el.innerText) != 'undefined') ? el.innerText : (typeof(el.textContent) != 'undefined') ? el.textContent : el.innerHTML.replace(/<[^>]+>/g, ''); }, findFirstHeader: function(node) { // a recursive function which returns the first header it finds inside // node, or null if there are no functions inside node. var nn = node.nodeName.toLowerCase(); if (nn.match(/^h[1-6]$/)) { // this node is itself a header; return our name return nn; } else { for (var i=0; i<node.childNodes.length; i++) { var subvalue = generated_toc.findFirstHeader(node.childNodes[i]); // if one of the subnodes finds a header, abort the loop and return it if (subvalue) return subvalue; } // no headers in this node at all return null; } }, init: function() { // quit if this function has already been called if (arguments.callee.done) return; // flag this function so we don't do the same thing twice arguments.callee.done = true; generated_toc.generate(); }};(function(i) {var u =navigator.userAgent;var e=/*@cc_on!@*/false; var st =setTimeout;if(/webkit/i.test(u)){st(function(){var dr=document.readyState;if(dr=="loaded"||dr=="complete"){i()}else{st(arguments.callee,10);}},10);}else if((/mozilla/i.test(u)&&!/(compati)/.test(u)) || (/opera/i.test(u))){document.addEventListener("DOMContentLoaded",i,false); } else if(e){ (function(){var t=document.createElement('doc:rdy');try{t.doScroll('left');i();t=null;}catch(e){st(arguments.callee,0);}})();}else{window.onload=i;}})(generated_toc.init);</script><div> <div> <div id="generated-toc"></div> <h1>foo</h1> <h2>bar</h2> </div> <h1>quux</h1></div>