在HTML select中复制数据(选项)

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

<select id="targetSelect"></select>

// 获取源select元素和目标select元素
var sourceSelect = document.getElementById("sourceSelect");
var targetSelect = document.getElementById("targetSelect");

// 复制选项
for (var i = 0; i < sourceSelect.options.length; i++) {
  var option = document.createElement("option");
  option.text = sourceSelect.options[i].text;
  option.value = sourceSelect.options[i].value;
  targetSelect.add(option);
}