代码示例:(标识:event_cancelable)
<!DOCTYPE html>
<html>
<body>

<p>点击按钮查看 onclick 事件是否为可取消事件。</p>

<button onclick="myFunction(event)">试一试</button>

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

<script>
function myFunction(event) { 
  var x = event.cancelable;
  document.getElementById("demo").innerHTML = x;
}
</script>

</body>
</html>
运行结果: