只提醒一次？运行完整功能后

Question

您如何才能使警报只发生一次？

$.ajax({
  url: '//cdnjs.cloudflare.com/ajax/libs/jquery.appear/0.3.3/jquery.appear.js',
  dataType: 'script',
  cache: true,
  success: function() {
    $("#footer").appear();

    $("body").on("appear", "#footer", function() {
      alert('Footer');
    });
  }
});

Answer 1

如果您希望处理程序只触发一次，则使用.one()注册事件处理程序

$.ajax({
  url: '//cdnjs.cloudflare.com/ajax/libs/jquery.appear/0.3.3/jquery.appear.js',
  dataType: 'script',
  cache: true,
  success: function() {}
}).done(function() {
  $("#footer").appear();

  $("body").one("appear", "#footer", function() {
    alert('Footer');
  });
});

div {
  height: 1000px;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div></div>
<footer id="footer">asdf</footer>