使用.text时返回"Undefined“？

Question

我知道使用.value可以获得所选项目的值，但我需要的是所选项目的名称。例如，我有一个包含两个项目的下拉菜单: Class 1和Class 2。Class 1的值为50，Class 2的值为60。如果我使用DMT5.value (Class 1的值)，我会得到50，但我需要的是名称本身，即"Class 1“。因此，我尝试使用以下代码：

var classRate = document.getElementById("DMT5")
var selectedClassRate = classRate.options[classRate.selectedIndex].text

但是，我得到一个错误:无法获取未定义或空引用的属性'text‘

*编辑:这里是DMT5：

<td style="padding-right: 9px;">
                                    <select id="DMT5" onchange="jCalculate()" style="width: 143px; padding: 2px 5px 2px 5px;">
                                    <option></option>
                                    <script runat="server" language="cache">
                                                            do INIT^CSP999
                                                            #import MX

                                                            set Origin=$g(%session.Data("VIPRates","Origin"))
                                                            set ID=$g(%session.Data("VIPRates","ID"))

                                                            &sql(DECLARE cCursor0 CURSOR FOR
                                                                SELECT VIPRatesItems_Class1, VIPRatesItems_Class2 
                                                                INTO :r1,:r2
                                                                FROM MX.VIPRates_VIPRatesItems
                                                                WHERE VIPRates->Customer->CustCode=:ID AND VIPRatesItems_Country=:Origin)

                                                            &sql(OPEN cCursor0)
                                                            &sql(FETCH cCursor0)
                                                            WHILE SQLCODE=0{
                                                                w "<option value='"_r1_"'>Class 1</option>"
                                                                w "<option value='"_r2_"'>Class 2</option>"
                                                                &sql(FETCH cCursor0)
                                                            }
                                                            &sql(CLOSE cCursor0)


                                                        </script>
                                    </select> </td>
                                </tr>

这是我的JS：

function jCalculate(){
document.getElementById("s1").style.display="inline"
document.getElementById("s2").style.display="inline"
document.getElementById("s4").style.display="inline"
    var UnitMeasure="kg"
    var Country=PackageT8.value

    var Dm = 3500
    repack = 0
    Dimension=0
    Volumetric=0
    SelectedWt=0
    OtherCharges=0  

    if (Country == "UNITED STATES OF AMERICA") {

        var Class1 = DMT5.value
        var Dm  = 166
    }
    else if (Country == "UNITED KINGDOM") {
        var Class1 = DMT5.value
        Dm=6000
        alert(DMT5.value)
    }
    else if (Country == "HONG KONG") {
        var Class1 = DMT5.value
    }
    else if (Country == "CHINA") {
        var Class1 = DMT5.value     
    }
    else if (Country == "SINGAPORE") {
        var Class1 = DMT5.value     
    }

    if (Country == "UNITED STATES OF AMERICA") {
        var Class2 = DMT5.value
    }
    else if (Country == "UNITED KINGDOM") {
        var Class2 = DMT5.value
    }
    else if (Country == "HONG KONG") {
        var Class2 = DMT5.value
    }
    else if (Country == "CHINA") {
        var Class2 = DMT5.value
    }
    else if (Country == "SINGAPORE") {
        var Class2 = DMT5.value
    }

    var Volumetric= (DMT1.value*DMT2.value*DMT3.value)/Dm
    if (isNaN(Volumetric)) var Volumetric=0

    if(Volumetric % 1 != 0) Volumetric=Volumetric+1
    var Volumetric=parseInt(Volumetric)

    if (DMT5.selectedIndex=="1") var ClassAmt=Class1
    if (DMT5.selectedIndex=="2") var ClassAmt=Class2

    var ActualWt=DMT6.value
    if (isNaN(ActualWt)) var ActualWt=0
    if (ActualWt>Volumetric)var SelectedWt=ActualWt
    if (ActualWt<=Volumetric)var SelectedWt=Volumetric

    var VAT=(SelectedWt*ClassAmt)*(12/100)
    if (isNaN(VAT)) var VAT=0

    if (CB1.checked==true){
        var repack=3
    }

    var AmountDue=(SelectedWt*ClassAmt)+ VAT 

    if (isNaN(AmountDue)) var AmountDue=0

    if (Country=="U.S.A"){
    var UnitMeasure="lb/s"
    }

    DMT9.value=SelectedWt
    DMT11.value=ClassAmt
    DMT12.value=Volumetric
    document.getElementById("AmountDue").innerHTML=AmountDue.toFixed(2)
    document.getElementById("s1").innerHTML="Volumetric Weight: "+Volumetric + UnitMeasure
    document.getElementById("s2").innerHTML="Chargable Weight: "+SelectedWt + UnitMeasure
    document.getElementById("s3").style.display="inline"

    //----OTHER CHARGES
    if (Country=="U.S.A"){
        var Volumetric=((DMT1.value  * 2.54) * (DMT2.value  * 2.54) * (DMT3.value  * 2.54))/3500
        if (isNaN(Volumetric)) var Volumetric=0
        if(Volumetric % 1 != 0) Volumetric=Volumetric+1
        var Volumetric=parseInt(Volumetric)

        var ActualWt=DMT6.value
        ActualWt=ActualWt/2.2
        if(ActualWt% 1 != 0) ActualWt=ActualWt+1
        var ActualWt=parseInt(ActualWt)


        if (isNaN(ActualWt)) var ActualWt=0
        if (ActualWt>Volumetric)var SelectedWt=ActualWt
        if (ActualWt<=Volumetric)var SelectedWt=Volumetric
    }


    if (SelectedWt<=3 ){
        if (Country=="U.S.A"){
            Dimension =  ((DMT1.value  * 2.54) * (DMT2.value  * 2.54) * (DMT3.value  * 2.54))/3500
        }
        else{
            Dimension =  (DMT1.value  * DMT2.value  * DMT3.value)/3500
        }

        if (isNaN(Dimension )) var Dimension = 0
        if(Dimension % 1 != 0) Dimension =Dimension +1
        var Dimension =parseInt(Dimension )


        if ((DMT4.value=="MMnl" || DMT4.value=="Luzon") && (Country!="U.S.A")){
            var OtherCharges = 4.48
        }
        else if ((DMT4.value=="Visayas" || DMT4.value=="Mindanao") && (Country!="U.S.A")){
            var OtherCharges = 4.62 
        }
        else if(DMT4.value=="Luzon"){
            var OtherCharges = 4.48 
        }
        else if (DMT4.value=="Visayas" || DMT4.value=="Mindanao"){
            var OtherCharges = 4.62     
        }

    }

    if (SelectedWt>=4){     
        if (Country=="U.S.A"){
            Dimension =  ((DMT1.value  * 2.54) * (DMT2.value  * 2.54) * (DMT3.value  * 2.54))/3500
        }
        else{
            Dimension =  (DMT1.value  * DMT2.value  * DMT3.value)/3500
        }

        if (isNaN(Dimension )) var Dimension =0
        if(Dimension % 1 != 0) Dimension =Dimension +1
        var Dimension =parseInt(Dimension )

        if ((DMT4.value=="MMnl" || DMT4.value=="Luzon") && (Country!="U.S.A")){
            var OtherCharges = 2.30 * Dimension 
        }
        else if ((DMT4.value=="Visayas" || DMT4.value=="Mindanao") && (Country!="U.S.A")){
            var OtherCharges = 2.50 * Dimension 
        }
        else if(DMT4.value=="Luzon"){
            var OtherCharges = 2.30 * Dimension 
        }
        else if (DMT4.value=="Visayas" || DMT4.value=="Mindanao"){
            var OtherCharges = 2.50 * Dimension         
        }
    }

    if (Country=="U.S.A" && DMT4.value=="MMnl"){
        var OtherCharges=0
    }

    if (PaymentT3.value=="For Pick Up"){
        var OtherCharges=0
    }
    var AmountDue=AmountDue+OtherCharges+repack
    if (isNaN(AmountDue)) var AmountDue=0

    DMT7.value=VAT.toFixed(2)
    DMT8.value=OtherCharges.toFixed(2)


    #server(..cAmountInPeso(AmountDue.toFixed(2),DMT13.value,DMT14.value))#
    document.getElementById("s4").innerHTML="Delivery Charges: USD "+ OtherCharges.toFixed(2)

}

我想我已经用'selectedIndex‘解决了这个问题。我获取所选项目的索引。

Answer 1

使用getAttribute

 classRate.options[classRate.selectedIndex].getAttribute("name");

Answer 2

if(classRate.options.length > classRate.selectedIndex) 
    var selectedClassRate = classRate.options[classRate.selectedIndex].text;