将值与从下拉列表中获取的项进行匹配

// HTML代码
<select id="dropdown">
  <option value="option1">选项1</option>
  <option value="option2">选项2</option>
  <option value="option3">选项3</option>
</select>

<input type="text" id="inputValue" placeholder="输入值">

<button onclick="matchValue()">匹配</button>

// JavaScript代码
function matchValue() {
  var dropdown = document.getElementById("dropdown");
  var inputValue = document.getElementById("inputValue").value;
  
  for (var i = 0; i < dropdown.options.length; i++) {
    if (dropdown.options[i].value === inputValue) {
      alert("找到匹配项：" + dropdown.options[i].text);
      return;
    }
  }
  
  alert("未找到匹配项");
}