如何实现两个文本框同时输入
<!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" lang="zh-CN"> <head> <meta http-equiv="Content-Type" content="text/html; charset=gb2312" /> <title></title> </head> <body> <script language="javascript"> function copyob1toob2(){ document.all["ob_text_2"].value=document.all["ob_text_1"].value } </script> <input type="text" id="ob_text_1" size=20 onkeyup="copyob1toob2()"> <input type="text" id="ob_text_2" size=20> </body> </html>