根据选择的值/月/年更改日期

// HTML部分
<select id="selectValue">
  <option value="1">1</option>
  <option value="2">2</option>
  <option value="3">3</option>
  <!-- 其他选项 -->
</select>

<select id="selectMonth">
  <option value="1">January</option>
  <option value="2">February</option>
  <option value="3">March</option>
  <!-- 其他选项 -->
</select>

<select id="selectYear">
  <option value="2022">2022</option>
  <option value="2023">2023</option>
  <option value="2024">2024</option>
  <!-- 其他选项 -->
</select>

<input type="text" id="displayDate" readonly>

// JavaScript部分
const selectValue = document.getElementById('selectValue');
const selectMonth = document.getElementById('selectMonth');
const selectYear = document.getElementById('selectYear');
const displayDate = document.getElementById('displayDate');

function updateDate() {
  const value = selectValue.value;
  const month = selectMonth.value;
  const year = selectYear.value;

  // 根据选择的值/月/年来生成日期
  const date = new Date(year, month - 1, value);

  // 格式化日期显示
  const formattedDate = `${date.getFullYear()}-${date.getMonth() + 1}-${date.getDate()}`;

  // 更新日期显示
  displayDate.value = formattedDate;
}

// 监听选择框的变化事件
selectValue.addEventListener('change', updateDate);
selectMonth.addEventListener('change', updateDate);
selectYear.addEventListener('change', updateDate);