[dabi]

הסתדרתי

<script language="javascript">
(function() {
    var i = 0;
    window.addfile = function() {
        var input = document.createElement('input');
        input.type = 'file';
        input.name = 'file' + i++;

        document.getElementById('form_name').appendChild(input);
    }
})();

</script>

<form id="form_name">
    
    
    <input type="button" onclick="addfile();" value="add file input" />
    
</form>