如何从下拉列表中获取所选选项并与输入字段相乘

<select id="dropdown">
  <option value="1">选项1</option>
  <option value="2">选项2</option>
  <option value="3">选项3</option>
</select>

<input type="number" id="inputField" />

var dropdown = document.getElementById("dropdown");
var inputField = document.getElementById("inputField");

dropdown.addEventListener("change", calculate);
inputField.addEventListener("input", calculate);

function calculate() {
  var selectedOption = dropdown.value;
  var inputFieldValue = inputField.value;

  var result = selectedOption * inputFieldValue;

  // 将结果显示在页面上
  var resultElement = document.getElementById("result");
  resultElement.textContent = "结果：" + result;
}

<div id="result"></div>