为什么不是'；这个Javascript计算器不能工作

基本上我有这个表单，它的字段由php和mysql填充。我正试图根据他们选择的区域和数量来获得我正在使用的javascript计算。但由于某种原因，它不起作用。我的代码在下面。有什么原因吗？

这是我的Javascript代码

        function getQuote() {
            var quantity = document.getElementByName("qty").value;
            var zoneSeat = document.getElementByName("zone").value;
            var quote;
            if (zoneSeat == "balcony") {
                quote= quantity*27;
            }
            else if (zoneSeat == "box 1" || "box 2") {
                quote= quantity*75;
            }
            else if (zoneSeat == "box 3" || "box 4") {
                quote= quantity*60;
            }
            else if (zoneSeat == "front stalls") {
                quote= quantity*22.50;
            }
            else  {
                quote = quantity*15;
            }
        }
    document.getElementById("quotation").value = quote;
}

这是我的表格

<form class="formDesign" action = "process.php" method="post">
        <fieldset>

                <p><label for="row">Row: </label><select name="row"></p>
                    <?php 
                        $strRow = "SELECT DISTINCT RowNumber FROM Seat";
                        $result = $con->query($strRow);
                    ?>
                    <?php while ($row = $result->fetch_row()): ?>
                    <?php $i = $row[0]; ?>
                    <option><?php echo $i; ?></option>
                <?php 
                $i++;
                endwhile;?> 
                </select>

                    <p><label for="seat">Zone: </label><select name="zone"></p>
                    <?php 
                        $strZone = "SELECT * FROM Zone";
                        $result = $con->query($strZone);
                    ?>
                    <?php while ($row = $result->fetch_row()): ?>
                    <?php $i = $row[0];?>
                    <option><?php echo $i?></option>
                <?php 
                $i++;
                endwhile;?> 
                </select>
                <p><label for="numberOfTickets">Quantity: 
                </label><input type="number" name="qty" min="1" max="5"></p>
                <p><input class="mybutton" name="Quote" value="Calculate quote" onclick="getQuote();"></p>  
                <label>£:</label><input name="quotation" id="quotation" type="text" readonly="readonly" value="total cost"/>
                <p><input type="submit" name= "sub"></p>
        </fieldset>
    </form>

            <p><label for="row">Row: </label><select name="row"></p>
            <?php 
                $strRow = "SELECT DISTINCT RowNumber FROM Seat";
                $result = $con->query($strRow);
            ?>
            <?php while ($row = $result->fetch_row()): ?>
            <?php $i = $row[0]; ?>
            <option><?php echo $i; ?></option>
        <?php 
        $i++;
        endwhile;?> 
        </select>

            <p><label for="seat">Zone: </label><select name="zone"></p>
            <?php 
                $strZone = "SELECT * FROM Zone";
                $result = $con->query($strZone);
            ?>
            <?php while ($row = $result->fetch_row()): ?>
            <?php $i = $row[0];?>
            <option><?php echo $i?></option>
        <?php 
        $i++;
        endwhile;?> 
        </select>
        <p><label for="numberOfTickets">Quantity: 
        </label><input type="number" name="qty" min="1" max="5"></p>
        <p><input class="mybutton" name="Quote" value="Calculate quote" onclick="getQuote();"></p>  
        <label>£:</label><input name="quotation" id="quotation" type="text" readonly="readonly" value="total cost"/>
        <p><input type="submit" name= "sub"></p>
</fieldset>

这是在区域表中插入数据库的内容

insert into Zone values ('rear stalls', 1.00);
insert into Zone values ('front stalls', 1.50);
insert into Zone values ('balcony', 1.80);
insert into Zone values ('box 1', 5.00);
insert into Zone values ('box 2', 5.00);
insert into Zone values ('box 3', 4.00);
insert into Zone values ('box 4', 4.00);

这是SQL语句

CREATE TABLE Zone(
 Name char(12) not null,
 PriceMultiplier float not null default 1.0, 
 PRIMARY KEY (Name)
);