如何在JS中使用html select标记

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

var selectElement = document.getElementById("mySelect");

var selectedValue = selectElement.value;

var selectedText = selectElement.options[selectElement.selectedIndex].text;

selectElement.value = "option2";

var option = document.createElement("option");
option.value = "option4";
option.text = "Option 4";
selectElement.add(option);

selectElement.remove(index); // index为选项的索引