总共包含三个页面（Html），分别为Parent.Html、ChildA.Html、ChildB.Html
Parent.Html页面代码
<frameset cols="50%,*"> <frame name="left" src="1.html"> <frame name="right" src="2.html"> </frameset>
ChildA.Html页面代码
<html> <head> <script> function setValue() { window.parent.document.getElementById("right").contentWindow.document.getElementById("txt2").value = document.getElementById("txt1").value; } </script> </head> <body> <input type="text" id="txt1" onkeyup="setValue()" /> </body> </html>
ChildB.Html页面代码
<html> <head> <script> function setValue() { window.parent.document.getElementById("left").contentWindow.document.getElementById("txt1").value = document.getElementById("txt2").value; } </script> </head> <body> <input type="text" id="txt2" onkeyup="setValue()" /> </body> </html>
原文：http://www.cnblogs.com/xiaocaibaodao/p/4095257.html