<!DOCTYPE HTML><html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"><title>無標題文檔</title></head><body><div>? javascript ?? <p>javascript</p>? <div>jQuery</div>? <h5>PHP</h5></div><script type="text/javascript">?var div = document.getElementsByTagName('div')[0].childNodes;?for(var a in div){? ? document.write(div[a].nodeName+' ? '+div[a].nodeValue+" ? "+div[a].nodeType+'<br/>'); ? ??}??</script></body></html>以下為輸出：javascriptjavascriptjQueryPHP#text javascript 3P null 1#text 3DIV null 1#text 3H5 null 1#text 3undefined undefined undefinedundefined undefined undefinedundefined undefined undefinedundefined undefined undefinedundefined undefined undefinedundefined undefined undefined
為什么用for in輸出，會多輸出6組undefined
慕粉4345620
2016-11-30 20:54:14