实例 »

<p>输入你的年龄并点击按钮:</p>

<input id="age" value="18" />

<button onclick="myFunction()">点我</button>

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

<script>

  function myFunction() {

    var age, voteable;

    age = document.getElementById("age").value;

    voteable = (age < 18) ? "太年轻而不能" : "年龄够";

    document.getElementById("demo").innerHTML = voteable + "投票";

  }

</script>