<script language="JavaScript"><!--
function extract(what) {
    if (what.indexOf('/') > -1)
        answer = what.substring(what.lastIndexOf('/')+1,what.length);
    else
        answer = what.substring(what.lastIndexOf('\\')+1,what.length);
    alert(answer);
}
//--></script>

<form name="myform">
<input type="file" name="myfile">
<input type="button" value="Test" onClick="extract(this.form.myfile.value)">
</form>

use this script to get the name of the file that you want to upload even before uploading it

Getting File Name of File Upload

JavaScript