<!DOCTYPE html><html><head><meta charset="UTF-8"><title>Document</title></head><body><ul><li id="bj" value="beijing">北京<p>海淀</p>? 奧運</li><li id="sh" value="shanghai" >上海</li></ul><script>var A=document.getElementById("bj");var C=document.getElementsByTagName("p");alert(A.firstChild.nodeValue+C.firstChild.nodeValue+A.lastChild.nodeValue);</script></body></html>
為什么輸出結果是:c.firstchild is undefined ，不是已經(jīng)var C=document.getElementsByTagName("p")；了么
慕粉3541299
2016-10-10 16:55:17