try something like
<input id="txt1" value="1234567890">
<input type="button" value="separate" onclick="separate()">
<script language="javascript">
var a1, a2
function separate()
{
txt1.focus();
var sel1 = document.selection.createRange().duplicate(); var range = txt1.createTextRange();
var sel2 = sel1.duplicate();
sel2.setEndPoint("StartToStart",range);
a1 = sel2.text; sel2 = sel1.duplicate();
sel2.setEndPoint("EndToEnd",range);
a2 = sel2.text; sel1.select();
sel1.collapse(); alert("a1:"+a1+"\na2:"+a2);
}
</script>
<input id="txt1" value="1234567890">
<input type="button" value="separate" onclick="separate()">
<script language="javascript">
var a1, a2
function separate()
{
txt1.focus();
var sel1 = document.selection.createRange().duplicate(); var range = txt1.createTextRange();
var sel2 = sel1.duplicate();
sel2.setEndPoint("StartToStart",range);
a1 = sel2.text; sel2 = sel1.duplicate();
sel2.setEndPoint("EndToEnd",range);
a2 = sel2.text; sel1.select();
sel1.collapse(); alert("a1:"+a1+"\na2:"+a2);
}
</script>
<input type="button" value="separate" onclick="separate()">
<script language="javascript">
var a1, a2
function separate()
{
txt1.focus();
var sel1 = document.selection.createRange().duplicate(); var range = txt1.createTextRange();
var sel2 = sel1.duplicate(); sel2.moveStart("character",-1);
a1 = sel2.text; sel2 = sel1.duplicate();
sel2.moveEnd("character",1);
a2 = sel2.text; alert("a1:"+a1+"\na2:"+a2);
}
</script>
<input id="txt1" value="1234567890">
<input type="button" value="separate" onclick="separate()">
<script language="javascript">
var a1, a2
function separate()
{
txt1.focus();
var sel = document.selection.createRange();
sel.moveStart("character",-1);
a1 = sel.text;
sel.moveStart("character",1);
sel.moveEnd("character",1);
a2 = sel.text;
alert("a1:"+a1+"\na2:"+a2);
}
</script>