Loop through elements document.getElementsByClassName JavaScript

<div>
    <input type="text" class="textbox" value="T1" /><br />
    <input type="text" class="textbox" value="T2" /><br />
    <input type="text" class="textbox" value="T3" /><br /><br />
    <input type="button" value="Set Value" onclick="SetValue()" />
</div>
<script type="text/javascript">
    function SetValue() {
        var textboxes = document.getElementsByClassName("textbox");

        var values = "";
        for (var i = 0; i < textboxes.length; i++) {
            values += textboxes[i].value + " ";
        }
        alert(values);
    };
</script>