html运行实例（event_onchange

代码示例：（标识：event_onchange_1）

<!DOCTYPE html>
<html>
<body>

<p>请从列表中选择一辆新车。</p>

<select id="mySelect" onchange="myFunction()">
  <option value="Audi">Audi</option>
  <option value="BMW">BMW</option>
  <option value="Mercedes">Mercedes</option>
  <option value="Volvo">Volvo</option>
</select>

<p>当您选择一辆新车时，会触发一个函数，输出所选汽车的值。</p>

<p id="demo"></p>

<script>
function myFunction() {
  var x = document.getElementById("mySelect").value;
  document.getElementById("demo").innerHTML = "You selected: " + x;
}
</script>

</body>
</html>