Thanks the following codes. while in Firefox, you just need to invoke textElement.focus() method.
So here is how to position the caret end the end of a text field/text
area with IE4/5:
<script>
function setCaretToEnd (el) {
if (el.createTextRange) {
var v = el.value;
var r = el.createTextRange();
r.moveStart(&aposcharacter&apos, v.length);
r.select();
}
}
function insertAtEnd (el, txt) {
el.value += txt;
setCaretToEnd (el);
}
</script>
</head>
<body>
ONCLICK="insertAtEnd (this.form.aText,
this.form.a2ndText.value);"
>
ONCLICK="insertAtEnd (this.form.aTextArea,
this.form.a3rdText.value);"
>
http://www.faqts.com/knowledge_base/view.phtml/aid/17749/fid/53