javascript - 如果选择选项做某事

Question

我有形式。如果选择了某个选项，我想做点什么。我试试这个

if (document.getElementById('order-select').value == "Услуга") {
  alert("blabla");
};

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<select id="order-select">
  <option value="Услуга" class="item-1">Услуга</option>
  <option value="Строительный проект" class="item-2">Строительный проект</option>
</select>

问题:每次选择选项时，我都想提醒。需要帮助

Answer 1

您需要为 change event 附加一个事件监听器.

当事件被触发时，您可以通过 target object 访问元素在 event object 上.

document.getElementById('order-select').addEventListener('change', function (e) {
  if (e.target.value === "Услуга") {
    alert('Selected');
  }
});

<select id="order-select">
  <option class="item-1">--Select--</option>
  <option value="Услуга" class="item-2">Услуга</option>
  <option value="Строительный проект" class="item-3">Строительный проект</option>
</select>

Updated Example

document.getElementById('order-select').addEventListener('change', function (e) {
  if (e.target.value === "Услуга") {
    alert('Selected');
  }
});