There is only one text field on a HTML form. Users input some text, press Enter, submit the form, and the form is reloaded. The main use is barcode reading. I use the following code to set the focus to the text field:

<script language="javascript">
    <!--
            document.getElementById("#{id}").focus()
    //-->
</script>

It works most of the time (if nobody touches the screen/mouse/keyboard).

However, when the user click somewhere outside the field within the browser window (the white empty space), the cursor is gone. One a single field HTML form, how can I prevent the cursor from getting lost? Or, how to re-focus the cursor inside the field after the cursor is lost? thx!