등록된 회원인지 체크하는 소스입니다

<script language="javascript">
<!--
var LU_UserData = new Array();
// LU_UserData[Index] = [사용자 ID, 비밀번호];
LU_UserData[0] = ['ida', 'pwa'];
LU_UserData[1] = ['idb', 'pwb'];
LU_UserData[2] = ['idc', 'pwc'];
LU_UserData[3] = ['idd', 'pwd'];
LU_UserData[4] = ['ide', 'pwe'];

function LU_Command() {
        var LU_CheckStatus = false;

        with(document.LoginUser) {
                if(LU_UserID.value == false) {
                        alert('사용자 ID를 입력하세요.');
                        LU_UserID.select();
                } else
                if(LU_UserPW.value == false) {
                        alert('사용자 PW를 입력하세요.');
                        LU_UserPW.select();
                } else {
                        for(var i=0; i<LU_UserData.length; i++) {
                                if((LU_UserID.value == LU_UserData[i][0]) && (LU_UserPW.value == LU_UserData[i][1])) {
                                        LU_CheckStatus = true;
                                        break;
                                }
                        }

                        if(LU_CheckStatus == true) {
                                // 사용자가 있을시 명령
                                alert('User : '+LU_UserID.value+'\n\n'+i+'번째 사용자입니다.');
                        } else {
                                // 사용자가 없을시 명령
                                alert('User : '+LU_UserID.value+'\n\n등록된 사용자가 아닙니다.');
                        }
                }
        }
}
//-->
</script>

<form name="LoginUser">
ID : <input type="text" name="LU_UserID"><br>
PW : <input type="password" name="LU_UserPW"><br>
<input type="button" value="Login" onclick="LU_Command();">
<input type="reset" value="Reset">
</form>