function form_onkeydown() {
    if (event.keyCode == 13 && event.srcElement.nodeName != "TEXTAREA") {

        switch (event.srcElement.id) {
            //login.aspx       
            case "ctl00_txtKey":
                {
                    document.getElementById("btnSearch").click();
                    return false;
                }
                //Search/IC.aspx
            case "txtKey":
                {
                    document.getElementById("btnSearch").click();
                    return false;
                }
            case "txtNum1":
            case "txtNum2":
            case "txtNum3":
            case "txtNum4":
                {
                    document.getElementById("btnBuy").click();
                    return false;
                }
            case "ctl00_ContentPlaceHolder1_txtPassWord":
                {
                    document.getElementById("ctl00_ContentPlaceHolder1_btnSubmit").click();
                    return false;
                }
            default:
                {

                    //       alert(event.srcElement.id)
                    event.srcElement.focus();
                    return false;
                }
                event.srcElement.focus();
        }
    }
}
document.onkeydown = form_onkeydown;