회원가입 시 비밀번호 일치 체크하는 것을 어떻게 적용하는지 알고 싶습니다.

<li>
                    <label for="reg_mb_password" class="sound_only">비밀번호<strong class="sound_only">필수</strong></label>
                    <input type="password" name="mb_password" id="reg_mb_password" <?php echo $required ?> class="frm_input half_input
                    <?php echo $required ?>" minlength="3" maxlength="20" placeholder="비밀번호" onkeyup="pw_checking()">

                    <label for="reg_mb_password_re" class="sound_only">비밀번호 확인<strong>필수</strong></label>
                    <input type="password" name="mb_password_re" id="reg_mb_password_re" <?php echo $required ?> class="frm_input half_input right_input
                    <?php echo $required ?>" minlength="3" maxlength="20" placeholder="비밀번호 확인" onkeyup="pw_checking()">
                </li>