选择选项值并将值分配给var (javascript)

<select id="mySelect">
  <option value="option1">Option 1</option>
  <option value="option2">Option 2</option>
  <option value="option3">Option 3</option>
</select>

var selectedOption;

document.getElementById("mySelect").addEventListener("change", function() {
  selectedOption = this.value;
});

var selectedOption = prompt("Please enter the option value:");

// 可以在此处对用户输入进行验证和处理

<ul id="optionsList">
  <li>Option 1</li>
  <li>Option 2</li>
  <li>Option 3</li>
</ul>

var options = document.getElementById("optionsList").getElementsByTagName("li");
var selectedOption;

for (var i = 0; i < options.length; i++) {
  options[i].addEventListener("click", function() {
    selectedOption = this.innerHTML;
  });
}