Question

我无法为输入分配特定值。例如，当用户通过TicketType提示输入字母时，我希望将该字母转换为数字。所以说他们进入了B＆＃39;作为他们的TicketType，我想要＆＃39; B＆＃39;要转换为50所以我可以后者计算总成本。目前TotalPayment只显示NaN，我很困惑。

这是我的JavaScript代码：

function ticket() {

    var TicketType;
    TicketType = prompt("Please enter the type of ticket you require!");
    document.write("<br>");
    var TicketQty;
    TicketQty = prompt("Please enter the number of tickets you require!");
    TicketQty = parseInt(TicketQty);
    document.write("Number of Tickets:" + TicketQty);
    document.write("<br>");
    var TotalPayment =(TicketPrice) * (TicketQty);
    document.write("Total Payment is:" + TotalPayment);
    var TicketPrice;
    TicketPrice = parseInt(TicketPrice);

    if (TicketType == A) {
        TicketPrice == 100;
    }
    else if (TicketType == B) {
        TicketPrice == 75;
    }
    else if (TicketType == C){
        TicketPrice == 50;
    }
    else {
        document.write("Invalid Ticket Type");
    }
}

这是我的HTML代码：

<html>
<title>Ticket</title>
<h1>Ticket</h1>
<script src="test.js">   </script>
<script>calculate()</script>
</body>

Answer 1

您的字符串比较完全错误。我正在限制我的回答，因为这是你所要求的。

if (TicketType == A) {

需要：

if (TicketType === "A") {

此外，您必须清楚分配'='与比较'=='。

整个部分应该更像这样：

if (TicketType === "A") {
    TicketPrice = 100;
} else if (TicketType === "B") {
    TicketPrice = 75;
} else if (TicketType === "C")
    TicketPrice = 50;
else {
    document.write("Invalid Ticket Type");
}

当你有一个链接的if-then-elseif

时，查看switch语句

您的代码还有其他问题。 Here's a jsfiddle有一些修复和改进。

Answer 2

你需要改变两件事：

1：字符串比较

if (TicketType == A)

到

if (TicketType == 'A')

2：错误分配

TicketPrice == 100

到

TicketPrice = 100

Answer 3

尝试以下方法：

＆＃13;

var TicketType;
var TicketQty;
var TicketPrice;
function calculateticket() {
    TicketType = prompt("Please enter the type of ticket you require!");
    document.write("<br>");
    TicketQty = prompt("Please enter the number of tickets you require!");
    testType();
}

calculateticket();
function testType(){
    if(TicketType =='A' || TicketType == 'B' || TicketType == 'C'){
        if (TicketType == 'A') {
            TicketPrice = 100;
        } else if (TicketType == 'B') {
            TicketPrice = 75;
        }  else if (TicketType == 'C'){
          TicketPrice = 50;
        }
        
        TicketQty = parseInt(TicketQty);
        document.body.innerHTML += '<span id="text1"></span>';
        document.getElementById('text1').innerHTML = 'Total Payment is: '+TicketQty;
        document.write("<br>");
        var TotalPayment =(TicketPrice) * (TicketQty);
        document.body.innerHTML += '<span id="text2"></span>';
        document.getElementById('text2').innerHTML = 'Total Payment is: '+TotalPayment;
        TicketPrice = parseInt(TicketPrice);
    }
    else {
        if(document.getElementById('text1') != null){
            document.getElementById('text1').innerHTML = '';
        }
        if(document.getElementById('text2') != null){
            document.getElementById('text2').innerHTML = '';
        }
        document.write("Invalid Ticket Type");
    }
}

＆＃13;

Javascript：为输入字母指定特定值

3 个答案: