实现原理很简单，就是循环文章模块，并抽取其中的h2、h3标签，将其中的内容赋予给新建的title树。
代码如下：
HTML代码：
<div> <div id="article"> <h2>二级标题</h2> <h3>三级标题</h3> <p>hello hello hello hello hello hello hello hello hello hello hello hello</p> <h3>三级标题</h3> <h3>三级标题</h3> <h3>三级标题</h3> <h3>三级标题</h3> <p>hello hello hello hello hello hello hello hello hello hello hello</p> <h2>二级标题</h2> <h3>三级标题</h3> <h3>三级标题</h3> <p>world world world world world world world world world world world world world world world world world world world world world world world world world world world world world world world </p> <h3>三级标题</h3> <h3>三级标题</h3> <h2>二级标题</h2> <h3>三级标题</h3> <h3>三级标题</h3> <h2>二级标题</h2> <h3>三级标题</h3> <h3>三级标题</h3> <h2>二级标题</h2> <h3>三级标题</h3> <h3>三级标题</h3> </div> <div id="articleMenu_box"> <span id="articleMenu_open"></span> <ul id="articleMenu"> <span id="articleMenu_close"></span> </ul> </div></div>
CSS代码：
* { margin: 0; padding: 0; border: 0;}body { font: 16px/1.5;}ul li, ol li { list-style: none;}.contextBox { position: relative; width: 960px; margin: 0 auto;}#article { margin-left: 200px; border: 1px #eee solid; padding: 15px;}.articleMenu a { text-decoration: none; color: #333;}.articleMenu a:hover { color: #f85455;}.articleMenu-box { width: 170px; position: absolute; left: 10px; top: 10px;}.articleMenu { padding: 10px; border: 1px solid #ccc; box-shadow: 2px 2px 2px #eee;}.titleH2, .titleH3 { line-height: 1.5em;}.titleH2 { font-weight: bold;}.titleH3 { margin-left: 20px;}.articleMenu .articleMenu-close, .articleMenu-open { display: inline-block; position: absolute; right: 0; top: 0; height: 44px; width: 44px; cursor: pointer;}.articleMenu-open { background: url("http://www.dengzhr.com/wp-content/themes/dengzhr/images/icon_articleMenu_open.png") no-repeat 50% 50%; display: none;}.articleMenu .articleMenu-close { background: url("http://www.dengzhr.com/wp-content/themes/dengzhr/images/icon_articleMenu_close.png") no-repeat 50% 50%;}JavaScript代码：
var article = document.getElementById("article");var articleHgroupMenu = document.getElementById("articleMenu");// 关闭和展开文档树var articleMenu_open = document.getElementById("articleMenu_open");var articleMenu_close = document.getElementById("articleMenu_close");articleMenu_close.onclick = function() { articleHgroupMenu.style.display = "none"; articleMenu_open.style.display = "block";};articleMenu_open.onclick = function() { articleHgroupMenu.style.display = "block"; articleMenu_open.style.display = "none";};//titleHgroup(article, articleHgroupMenu, "titleH2", "titleH3");// 获得obj下的直接子元素中为标题h2~h3的标题元素// 参数说明：hgroupParent为包含h2和h3的直接父元素；MenuList为承载新建文章列表的ul元素；// h2ClassName、h3ClassName分别为新建文章列表中对应h2、h3的li自列表的Class属性；function titleHgroup(hgroupParent, MenuList, h2ClassName, h3ClassName) { var hgroup = hgroupParent.children; // 创建文档片段，来包裹自动生成的h2、h3对应生成的li列表 var fragment = document.createDocumentFragment(); for(i = 0; i < hgroup.length && hgroup[i].nodeType === 1; i++) { // 为对应类型的标题生成li列表 // 参数说明：hType为标题的类型如h1~h6；className为标题对应的li列表的class属性值； function titleToList(hType, className) { var li = document.createElement("li"); li.className = className; // 为li标签内部添加a标签，用锚点进行定位； hgroup[i].id= hType + i; li.innerHTML = ("<a href='#" + hType + i + "'>" + hgroup[i].innerHTML +"</a>"); fragment.appendChild(li); } // 当遍历中标题元素为h2时，调用titleToList(hType, className)新增对应的li列表； if(hgroup[i].nodeName.toLowerCase() == "h2") { titleToList("h2", h2ClassName); } // 当遍历中标题元素为h3时，调用titleToList(hType, className)新增对应的li列表； if(hgroup[i].nodeName.toLowerCase() == "h3") { titleToList("h3", h3ClassName); } } // 将承载好对应li元素集合的文档片段fragment添加到DOM(即在DOM中包裹li列表的父元素)中去； MenuList.appendChild(fragment);}完整实例代码
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=gb2312" /><title>原生JS实现自动生成文章标题树</title><style type="text/css">* { margin: 0; padding: 0; border: 0;}body { font: 16px/1.5;}ul li, ol li { list-style: none;}.contextBox { position: relative; width: 960px; margin: 0 auto;}#article { margin-left: 200px; border: 1px #eee solid; padding: 15px;}.articleMenu a { text-decoration: none; color: #333;}.articleMenu a:hover { color: #f85455;}.articleMenu-box { width: 170px; position: absolute; left: 10px; top: 10px;}.articleMenu { padding: 10px; border: 1px solid #ccc; box-shadow: 2px 2px 2px #eee;}.titleH2, .titleH3 { line-height: 1.5em;}.titleH2 { font-weight: bold;}.titleH3 { margin-left: 20px;}.articleMenu .articleMenu-close, .articleMenu-open { display: inline-block; position: absolute; right: 0; top: 0; height: 44px; width: 44px; cursor: pointer;}.articleMenu-open { background: url("http://www.dengzhr.com/wp-content/themes/dengzhr/images/icon_articleMenu_open.png") no-repeat 50% 50%; display: none;}.articleMenu .articleMenu-close { background: url("http://www.dengzhr.com/wp-content/themes/dengzhr/images/icon_articleMenu_close.png") no-repeat 50% 50%;}</style></head><body><div> <div id="article"> <h2>二级标题</h2> <h3>三级标题</h3> <p>hello<br /> hello<br /> hello<br /> hello<br /> hello<br /> hello<br /><br /> hello<br /> hell<br />o hel<br />lo hell<br />o he<br />llo hello</p> <h3>三级标题</h3> <h3>三级标题</h3> <h3>三级标题</h3> <h3>三级标题</h3> <p>hello hello hello hello hello hello hello hello hello hello hello</p> <h2>二级标题</h2> <h3>三级标题</h3> <h3>三级标题</h3> <p>world w<br />orld <br />world world wo<br />rld world wo<br />rld world world wor<br />ld world world <br />world <br />worl<br />d world<br /> w<br />orld <br />world wo<br />rld wor<br />ld world wor<br />ld world worl<br />d w<br />or<br />ld<br /> <br />world <br />world <br />world<br /> <br />wo<br />rld wo<br />rld w<br />orld w<br />orld </p> <h3>三级标题</h3> <h3>三级标题</h3> <h2>二级标题</h2> <h3>三级标题</h3> <h3>三级标题</h3> <h2>二级标题</h2> <h3>三级标题</h3> <h3>三级标题</h3> <h2>二级标题</h2> <h3>三级标题</h3> <h3>三级标题</h3> </div> <div id="articleMenu_box"> <span id="articleMenu_open"></span> <ul id="articleMenu"> <span id="articleMenu_close"></span> </ul> </div></div><script type="text/javascript">var article = document.getElementById("article");var articleHgroupMenu = document.getElementById("articleMenu");// 关闭和展开文档树var articleMenu_open = document.getElementById("articleMenu_open");var articleMenu_close = document.getElementById("articleMenu_close");articleMenu_close.onclick = function() { articleHgroupMenu.style.display = "none"; articleMenu_open.style.display = "block";};articleMenu_open.onclick = function() { articleHgroupMenu.style.display = "block"; articleMenu_open.style.display = "none";};//titleHgroup(article, articleHgroupMenu, "titleH2", "titleH3");// 获得obj下的直接子元素中为标题h2~h3的标题元素// 参数说明：hgroupParent为包含h2和h3的直接父元素；MenuList为承载新建文章列表的ul元素；// h2ClassName、h3ClassName分别为新建文章列表中对应h2、h3的li自列表的Class属性；function titleHgroup(hgroupParent, MenuList, h2ClassName, h3ClassName) { var hgroup = hgroupParent.children; // 创建文档片段，来包裹自动生成的h2、h3对应生成的li列表 var fragment = document.createDocumentFragment(); for(i = 0; i < hgroup.length && hgroup[i].nodeType === 1; i++) { // 为对应类型的标题生成li列表 // 参数说明：hType为标题的类型如h1~h6；className为标题对应的li列表的class属性值； function titleToList(hType, className) { var li = document.createElement("li"); li.className = className; // 为li标签内部添加a标签，用锚点进行定位； hgroup[i].id= hType + i; li.innerHTML = ("<a href='#" + hType + i + "'>" + hgroup[i].innerHTML +"</a>"); fragment.appendChild(li); } // 当遍历中标题元素为h2时，调用titleToList(hType, className)新增对应的li列表； if(hgroup[i].nodeName.toLowerCase() == "h2") { titleToList("h2", h2ClassName); } // 当遍历中标题元素为h3时，调用titleToList(hType, className)新增对应的li列表； if(hgroup[i].nodeName.toLowerCase() == "h3") { titleToList("h3", h3ClassName); } } // 将承载好对应li元素集合的文档片段fragment添加到DOM(即在DOM中包裹li列表的父元素)中去； MenuList.appendChild(fragment);}</script></body></html>总结
以上就是利用原生JS自动生成文章标题树的全部内容，希望本文的内容对大家能有所帮助，如果有疑问可以留言讨论。