Validation to Allow only Alphabets and Space using Regular Expression and JavaScript

<input type="text" id="txtState" />
<input type="button" id="btnValidate" value="Submit" />
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
<script type="text/javascript">
    $("#btnValidate").live("click", function () {
        var regex = /^[a-zA-Z ]*$/;
        if (regex.test($("#txtState").val())) {
            alert("Valid");
        } else {
            alert("Invalid");
        }
    });
</script>