<form name="post" method="post" action="">
<input name="text1" type="text" id="text1" onchange="aaa();">
<input name="text2" type="text" id="text2">
</form><SCRIPT LANGUAGE=javascript>
<!--
function aaa()
{
var vvv;
vvv=post.text1.value;
document.post.text2.value=vvv.substring(1,5);
}
//-->
</SCRIPT>
<input name="text1" type="text" id="text1" onchange="aaa();">
<input name="text2" type="text" id="text2">
</form><SCRIPT LANGUAGE=javascript>
<!--
function aaa()
{
var vvv;
vvv=post.text1.value;
document.post.text2.value=vvv.substring(1,5);
}
//-->
</SCRIPT>
<input name="text1" type="text" id="text1" onkeypress="return aaa();">
<input name="text2" type="text" id="text2">
</form><SCRIPT LANGUAGE=javascript>
<!--
function aaa()
{
var vvv;
vvv=post.text1.value;
document.post.text2.value=vvv.substring(2,6);
}
//-->
</SCRIPT>
要么这样试试
<input name="text1" type="text" id="text1" onchange="return aaa();" onkeydown="return aaa();">onchange是当你focus离开text1时才调用的。