我是编程/编码的新手，所以这对大多数人来说可能很容易。 我应该创建一个用于权重转换的 Web 应用程序：从美元到日元和从日语 日元 为 美元。假设 1 美元 = 112.57 日元 - 使用一个输入框 - 使用下拉菜单选择要执行的转换 - 两个公式是：日元=美元*112.57和美元=日元/112.57
这是我到目前为止得到的：
<!DOCTYPE html>
<html>
<head>
<script>
function convert()
{
var Dollars, Yen; //declare variables
//INPUT
if (inCurrency.value == "U.S Dollars to Yen") {x.value=Dollars}
else if (inCurrency.value == "Yen to U.S Dollars") {x.value=Yen}
//PROCESSING
Yen = Dollars * 112.57;
Dollars = Yen / 112.57;
//OUTPUT
spYen.innerHTML = Yen;
spDollars.innerHTML = Dollars;
}
</script>
<style>
.CCC {
font-family: Arial;
font-size: 12pt;
color: lightseagreen;
}
.DDD {
font-family: 'Times New Roman', Times, serif;
font-size: 12pt;
color: lawngreen;
}
</style>
</head>
<body>
<h2>Currency Converter</h2>
<span class="CCC">Select one:</span>
<select id="inCurrency">
<option>U.S Dollars to Yen</option>
<option>Yen to U.S Dollars</option>
</select><br />
<span style="color:deeppink">Enter amount </span><span id="x"></span><input
type="text" /><br />
<i>
<span class="DDD">Dollars: </span><span id="spDollars"></span><br />
<span class="DDD">Yen: </span><span id="spYen"></span><br />
</i>
<input type="button" value="Convert Currency" onClick="convert()" />
<br />
<br />
<a href="Index.html">Home
</body>
</html>
这就是我遇到的问题，是头部部分的实际编码。我不确定如何正确设置它，因此它会执行方程。我想知道是否有人可以提供帮助。谢谢。
这是获得所需结果的一种方式。 我已经为您修复了HTML和Javascript。
直接尝试获取/设置 id 值不是正确的方法。
function convert()
{
var Dollars, Yen; //declare variables
//INPUT
var e = document.getElementById("inCurrency");
var inCurrency = e.options[e.selectedIndex].text;
var amount = document.getElementById("x").value;
//PROCESSING
if (inCurrency == "U.S Dollars to Yen")
{
Dollars = amount;
Yen = Dollars * 112.57;
}
else if (inCurrency == "Yen to U.S Dollars")
{
Yen = amount;
Dollars = Yen / 112.57;
}
//OUTPUT
document.getElementById("spYen").innerHTML = Yen;
document.getElementById("spDollars").innerHTML = Dollars;
}.CCC {
font-family: Arial;
font-size: 12pt;
color: lightseagreen;
}
.DDD {
font-family: 'Times New Roman', Times, serif;
font-size: 12pt;
color: lawngreen;
}<h2>Currency Converter</h2>
<span class="CCC">Select one:</span>
<select id="inCurrency">
<option>U.S Dollars to Yen</option>
<option>Yen to U.S Dollars</option>
</select><br />
<span style="color:deeppink">Enter amount </span><input id="x" type="text" /><br />
<i>
<span class="DDD">Dollars: </span><span id="spDollars"></span><br />
<span class="DDD">Yen: </span><span id="spYen"></span><br />
</i>
<input type="button" value="Convert Currency" onClick="convert()" />
<br />
<br />
<a href="Index.html">Homefunction convert()
{
convertRule = document.querySelector("#inCurrency").value;
amount = document.querySelector("#amount").value;
if (inCurrency.value == "U.S Dollars to Yen"){
Yen = amount * 112.57;
document.getElementById("spDollars").innerHTML = Yen
}else{
Dollars = amount * 122.22;
document.getElementById("spDollars").innerHTML = Dollars
}
}