​x
 
<!DOCTYPE html>
<html>
<head>
<script>
function myFunction() {
  document.getElementById("demo").innerHTML = "Hello World!";
}
</script>
</head>
​
<body>
​
<p>单击“试一试”时，将调用一个函数。</p>
​
<p>该功能将显示一条消息。</p>
​
<button onclick="myFunction()">试一试</button>
​
<p id="demo"></p>
​
</body>
</html>
​