<!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=utf-8" /> <title>explaining</title> </head> <body> <h1>What is the Document Object Model</h1> <p>The <abbr title='World Wide Web Consortium'>W3C</abbr> defines the <abbr title='Document Object Model'>DOM</abbr> as:</p> <blockquote cite="http://www.w3.org/DOM/"> <P> A platform- and language-neutral interface that will allow programs and scripts to dynamically access and update the content,structure the style of document.</P> </blockquote> <p> It is an <abbr title='Application Programming Interface'>API</abbr> that can be used to navigate <abbr title='HyperText Markup Language'>HTML</abbr> and <abbr title="eXtensible Markup Language">XML</abbr> documents. </p> <script> addLoadEvent(displayCitations); function displayCitations(){ if( !document.getElementsByTagName || !document.getElementById || !document.createTextNode ) return false; var quotes=document.getElementsByTagName('blockquote'); for(var i=0;i<quotes.length;i++){ if( !quotes[i].getAttribute('cite')) continue; //使用continue立刻跳到下一次循环 var url=quotes[i].getAttribute('cite'); var quoteElements=quotes[i].getElementsByTagName('*'); if( quoteElements.length < 1) continue; var elem=quoteElements[quoteElements.length-1]; var link=document.createElement('a'); link.setAttribute('href',url); var link_text=document.createTextNode('source'); link.appendChild(link_text); var superscript=document.createElement('sup'); superscript.appendChild(link); elem.appendChild(superscript); console.log(elem); } } function addLoadEvent(func){ var oldEvent = window.onload; if( typeof window.onload != 'function'){ window.onload=func; }else{ window.onload=function(){ oldEvent(); func(); } } } </script> </body> </html>
解析：
<blockquote cite="http://www.w3.org/DOM/"> <P> A platform- and language-neutral interface that will allow programs and scripts to dynamically access and update the content,structure the style of document.</P> </blockquote>
找到blockquote下的块级元素，若用document.getElementsByTagName('blockquote').lastChild 乍看起来，是查找到最后一个元素
事实上，那个p节点的确是blockquote元素的最后一个元素节点，但在</p>和</blockquote>标签之间还存在一个换行符。有些浏览器会
把这个换行符解释为一个文本节点。这样一 来，blockquote元素节点的lastChild属性就将是一个文本节点而不是元素节点。
解决方法：查找所有的元素节点，最后一个元素节点即为p
document.getElementsByTagName('blockquote').getElementsByTagName('*')[length-1]