Allow user to enter specific Characters in TextBox using JavaScript

Alphanumeric value:
<input type="text" id="text1" onkeypress="return IsAlphaNumeric(event);" ondrop="return false;"
    onpaste="return false;" />
<span id="error" style="color: Red; display: none">* Character not allowed</span>
<script type="text/javascript">
    var specialKeys = new Array();
    specialKeys.push(47); // /
    specialKeys.push(40); // (
    specialKeys.push(41); // )
    specialKeys.push(38); // &
    specialKeys.push(45); // .
    specialKeys.push(46); // -
    specialKeys.push(32); // Space
    function IsAlphaNumeric(e) {
        var keyCode = e.keyCode == 0 ? e.charCode : e.keyCode;
        var ret = ((keyCode >= 48 && keyCode <= 57) || (keyCode >= 65 && keyCode <= 90) || (keyCode >= 97 && keyCode <= 122) || (specialKeys.indexOf(e.keyCode) != -1 && e.charCode == e.keyCode));
        document.getElementById("error").style.display = ret ? "none" : "inline";
        return ret;
    }
</script>