Javascript输入汉字自动转换为首字母的拼音码

  <script language="javascript" type="text/javascript">
function getPYCode(str) {
    var result = "";
    for (var i = 0; i < str.length; i++) {
        result += getPY(str.charAt(i).toString())
    }
    document.getElementById("lblResult").innerHTML = result
}
function getPY(s) {
    if (s != "") {
        execScript("tmp=asc(\"" + s + "\")", "vbscript");
        tmp = 65536 + tmp;
        var py = "";
        if (tmp >= 45217 && tmp <= 45252) {
            py = "A"
        } else if (tmp >= 45253 && tmp <= 45760) {
            py = "B"
        } else if (tmp >= 45761 && tmp <= 46317) {
            py = "C"
        } else if (tmp >= 46318 && tmp <= 46825) {
            py = "D"
        } else if (tmp >= 46826 && tmp <= 47009) {
            py = "E"
        } else if (tmp >= 47010 && tmp <= 47296) {
            py = "F"
        } else if ((tmp >= 47297 && tmp <= 47613) || (tmp == 63193)) {
            py = "G"
        } else if (tmp >= 47614 && tmp <= 48118) {
            py = "H"
        } else if (tmp >= 48119 && tmp <= 49061) {
            py = "J"
        } else if (tmp >= 49062 && tmp <= 49323) {
            py = "K"
        } else if (tmp >= 49324 && tmp <= 49895) {
            py = "L"
        } else if (tmp >= 49896 && tmp <= 50370) {
            py = "M"
        } else if (tmp >= 50371 && tmp <= 50613) {
            py = "N"
        } else if (tmp >= 50614 && tmp <= 50621) {
            py = "O"
        } else if (tmp >= 50622 && tmp <= 50905) {
            py = "P"
        } else if (tmp >= 50906 && tmp <= 51386) {
            py = "Q"
        } else if (tmp >= 51387 && tmp <= 51445) {
            py = "R"
        } else if (tmp >= 51446 && tmp <= 52217) {
            py = "S"
        } else if (tmp >= 52218 && tmp <= 52697) {
            py = "T"
        } else if (tmp >= 52698 && tmp <= 52979) {
            py = "W"
        } else if (tmp >= 52980 && tmp <= 53688) {
            py = "X"
        } else if (tmp >= 53689 && tmp <= 54480) {
            py = "Y"
        } else if (tmp >= 54481 && tmp <= 62289) {
            py = "Z"
        } else {
            py = s.charAt(0)
        }
        return py
    }
}
</script>  

HTML:

<input type="text" onkeydown="getPYCode(this.value)" onkeyup="getPYCode(this.value)" />

<label id="lblResult" style="color:Red"></label>