我正在尝试创建一个类似计算器的东西。我有一个自定义函数，它假设从两个变量加载输入值，并将它们放在一起，但它不起作用，所以我用控制台日志检查它是否加载了输入值，它所说的只是这些值未定义。你知道怎么解决这个问题吗？
let num1 = document.getElementById("number1").value,
num2 = document.getElementById("number2").value,
operator = document.getElementById("select"),
resolutor = document.getElementById("resolute"),
res = document.getElementById("result");
function mathoperation(num1, num2) {
let value = operator.value,
result;
switch (value) {
case "plus":
console.log(num1); //console says unindefied
console.log(num2); //console says unindefied
break;
}
}<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Úloha 18.1</title>
</head>
<body>
<input type="text" id="number1">
<select name="" id="select">
<option value="plus">+</option>
<option value="minus">-</option>
<option value="krat">*</option>
<option value="deleno">/</option>
</select>
<input type="text" id="number2">
<input type="button" id="resolute" value="=" onclick="mathoperation()">
<input type="text" id="result" readonly>
</body>
</html>
您必须在事件处理程序内部而不是外部获取输入元素的值
function mathoperation() {
let num1 = document.getElementById("number1").value,
num2 = document.getElementById("number2").value,
operator = document.getElementById("select"),
resolutor = document.getElementById("resolute"),
res = document.getElementById("result");
let value = operator.value,
result;
switch (value) {
case "plus":
console.log(num1); //console says unindefied
console.log(num2); //console says unindefied
break;
}
}<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Úloha 18.1</title>
</head>
<body>
<input type="text" id="number1">
<select name="" id="select">
<option value="plus">+</option>
<option value="minus">-</option>
<option value="krat">*</option>
<option value="deleno">/</option>
</select>
<input type="text" id="number2">
<input type="button" id="resolute" value="=" onclick="mathoperation()">
<input type="text" id="result" readonly>
</body>
</html>