javascript - 仅当 div 进入视口(viewport)时才使用 bootstrap 4 动画对 Angular 线 div

Question

我想在 2 个对 Angular 线 div 上运行动画。 第一个应该从右边出现，第二个应该从左边出现。我尝试了在互联网上找到的不同解决方案，因为这是我第一次制作动画，但没有达到预期效果。

<section class="page-section h-100 text-center text-white" id="services" >
    <div class="container-fluid toLeft" id="slideInRight">
        <div class="container">
            <h1>Sei in cerca di un PT?</h1>
            <p class="font-weight-light">Potrai entrare in contatto con il personal trainer perfetto per te. Inizia subito il tuo percorso verso il corpo dei tuoi sogni</p>
            <button id="signInAsUser" type="button" class="btn btn-dark loginService">Iscriviti come cliente</button>
        </div>
      </div>
      <div class="container-fluid toRight" id="slideInLeft">
        <div class="container">
          <h1>Sei un PT in cerca di clienti?</h1>
          <p class="font-weight-light">Potrai offrire le tue conoscenze tecniche agli utenti, aiutandoli a raggiungere i propri obiettivi</p>
          <button id="signInAsPt" type="button" class="btn btn-danger loginService">Iscriviti come PT</button>
        </div>
      </div>
</section>

演示:https://jsfiddle.net/4b6283m9/

动画代码:

$('.toLeft').each( function (i)){
  var bottom_of_object = $(this).offset().top + $(this).outerHeight();
  var bottom_of_window = $(window).scrollTop() + $(window).height();
  /* If the object is completely visible in the window, fade it it */
  if( bottom_of_window > bottom_of_object ){
     $(this).animate({'opacity':'1'},500);
  }
}

Answer 1

你需要的是CSS animations它也可以在没有 JavaScript 的情况下工作；根据您的要求，我们只需要使用 margin 属性来获得我们想要的效果...动画设置为 3 秒 的速度您可以更改...还有动画的速度曲线，当前设置为 ease-in-out;

UPDATE 根据以下提问者的评论: 只有当 div(我们想要设置动画)进入视口(viewport)时才会触发动画

工作代码段如下:

$(window).scroll(function() {
  var top_of_element = $("#slideInRight").offset().top;
  var bottom_of_element = $("#slideInRight").offset().top + $("#slideInRight").outerHeight();
  var bottom_of_screen = $(window).scrollTop() + $(window).innerHeight();
  var top_of_screen = $(window).scrollTop();

  if ((bottom_of_screen > top_of_element) && (top_of_screen < bottom_of_element)) {
    //console.log("the element is visible, do something");
    if ($("#slideInRight").hasClass("toLeft")) {} else {
      $("#slideInRight").addClass("toLeft");
    }
    if ($("#slideInLeft").hasClass("toRight")) {} else {
      $("#slideInLeft").addClass("toRight");
    }
  } else {
    // console.log("the element is not visible, do something else");
  }
});

.container-fluid {
  width: 100%;
  padding: 8rem 0;
}

.toLeft {
  background: #b31c2a;
  transform: skewY(-2deg);
  animation: enterFromLeft 3s ease-in-out;
}

@keyframes enterFromLeft {
  from {
    margin-left: -90%;
  }
  to {
    margin-left: 0%;
  }
}

.toLeft .container {
  transform: skewY(2deg);
}

.toRight {
  background: black;
  transform: skewY(2deg);
  animation: enterFromRight 3s ease-in-out;
}

@keyframes enterFromRight {
  from {
    margin-left: 90%;
  }
  to {
    margin-left: 0%;
  }
}

.toRight .container {
  transform: skewY(-2deg);
}

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css" />
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js"></script>
<p>
  The standard Lorem Ipsum passage, used since the 1500s "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi
  ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
  Section 1.10.32 of "de Finibus Bonorum et Malorum", written by Cicero in 45 BC "Sed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium doloremque laudantium, totam rem aperiam, eaque ipsa quae ab illo inventore veritatis et quasi
  architecto beatae vitae dicta sunt explicabo. Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui dolorem ipsum quia
  dolor sit amet, consectetur, adipisci velit, sed quia non numquam eius modi tempora incidunt ut labore et dolore magnam aliquam quaerat voluptatem. Ut enim ad minima veniam, quis nostrum exercitationem ullam corporis suscipit laboriosam, nisi ut aliquid
  ex ea commodi consequatur? Quis autem vel eum iure reprehenderit qui in ea voluptate velit esse quam nihil molestiae consequatur, vel illum qui dolorem eum fugiat quo voluptas nulla pariatur?" 1914 translation by H. Rackham "But I must explain to you
  how all this mistaken idea of denouncing pleasure and praising pain was born and I will give you a complete account of the system, and expound the actual teachings of the great explorer of the truth, the master-builder of human happiness. No one rejects,
  dislikes, or avoids pleasure itself, because it is pleasure, but because those who do not know how to pursue pleasure rationally encounter consequences that are extremely painful. Nor again is there anyone who loves or pursues or desires to obtain pain
  of itself, because it is pain, but because occasionally circumstances occur in which toil and pain can procure him some great pleasure. To take a trivial example, which of us ever undertakes laborious physical exercise, except to obtain some advantage
  from it? But who has any right to find fault with a man who chooses to enjoy a pleasure that has no annoying consequences, or one who avoids a pain that produces no resultant pleasure?" Section 1.10.33 of "de Finibus Bonorum et Malorum", written by
  Cicero in 45 BC "At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia
  deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas
  assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut
  reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat." 1914 translation by H. Rackham "On the other hand, we denounce with righteous indignation and dislike men who are so beguiled and demoralized by the charms
  of pleasure of the moment, so blinded by desire, that they cannot foresee the pain and trouble that are bound to ensue; and equal blame belongs to those who fail in their duty through weakness of will, which is the same as saying through shrinking from
  toil and pain. These cases are perfectly simple and easy to distinguish. In a free hour, when our power of choice is untrammelled and when nothing prevents our being able to do what we like best, every pleasure is to be welcomed and every pain avoided.
  But in certain circumstances and owing to the claims of duty or the obligations of business it will frequently occur that pleasures have to be repudiated and annoyances accepted. The wise man therefore always holds in these matters to this principle
  of selection: he rejects pleasures to secure other greater pleasures, or else he endures pains to avoid worse pains."

</p>

<hr/>
<p>
  The standard Lorem Ipsum passage, used since the 1500s "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi
  ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
  Section 1.10.32 of "de Finibus Bonorum et Malorum", written by Cicero in 45 BC "Sed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium doloremque laudantium, totam rem aperiam, eaque ipsa quae ab illo inventore veritatis et quasi
  architecto beatae vitae dicta sunt explicabo. Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui dolorem ipsum quia
  dolor sit amet, consectetur, adipisci velit, sed quia non numquam eius modi tempora incidunt ut labore et dolore magnam aliquam quaerat voluptatem. Ut enim ad minima veniam, quis nostrum exercitationem ullam corporis suscipit laboriosam, nisi ut aliquid
  ex ea commodi consequatur? Quis autem vel eum iure reprehenderit qui in ea voluptate velit esse quam nihil molestiae consequatur, vel illum qui dolorem eum fugiat quo voluptas nulla pariatur?" 1914 translation by H. Rackham "But I must explain to you
  how all this mistaken idea of denouncing pleasure and praising pain was born and I will give you a complete account of the system, and expound the actual teachings of the great explorer of the truth, the master-builder of human happiness. No one rejects,
  dislikes, or avoids pleasure itself, because it is pleasure, but because those who do not know how to pursue pleasure rationally encounter consequences that are extremely painful. Nor again is there anyone who loves or pursues or desires to obtain pain
  of itself, because it is pain, but because occasionally circumstances occur in which toil and pain can procure him some great pleasure. To take a trivial example, which of us ever undertakes laborious physical exercise, except to obtain some advantage
  from it? But who has any right to find fault with a man who chooses to enjoy a pleasure that has no annoying consequences, or one who avoids a pain that produces no resultant pleasure?" Section 1.10.33 of "de Finibus Bonorum et Malorum", written by
  Cicero in 45 BC "At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia
  deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas
  assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut
  reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat." 1914 translation by H. Rackham "On the other hand, we denounce with righteous indignation and dislike men who are so beguiled and demoralized by the charms
  of pleasure of the moment, so blinded by desire, that they cannot foresee the pain and trouble that are bound to ensue; and equal blame belongs to those who fail in their duty through weakness of will, which is the same as saying through shrinking from
  toil and pain. These cases are perfectly simple and easy to distinguish. In a free hour, when our power of choice is untrammelled and when nothing prevents our being able to do what we like best, every pleasure is to be welcomed and every pain avoided.
  But in certain circumstances and owing to the claims of duty or the obligations of business it will frequently occur that pleasures have to be repudiated and annoyances accepted. The wise man therefore always holds in these matters to this principle
  of selection: he rejects pleasures to secure other greater pleasures, or else he endures pains to avoid worse pains."

</p>

<section class="page-section h-100 text-center text-white" id="services">
  <div class="container-fluid " id="slideInRight"> /* toLeft */
    <div class="container">
      <h1>Sei in cerca di un PT?</h1>
      <p class="font-weight-light">Potrai entrare in contatto con il personal trainer perfetto per te. Inizia subito il tuo percorso verso il corpo dei tuoi sogni</p>
      <button id="signInAsUser" type="button" class="btn btn-dark loginService">Iscriviti come cliente</button>
    </div>
  </div>
  <div class="container-fluid " id="slideInLeft"> /* toRight */
    <div class="container">
      <h1>Sei un PT in cerca di clienti?</h1>
      <p class="font-weight-light">Potrai offrire le tue conoscenze tecniche agli utenti, aiutandoli a raggiungere i propri obiettivi</p>
      <button id="signInAsPt" type="button" class="btn btn-danger loginService">Iscriviti come PT</button>
    </div>
  </div>
</section>