[css] Using CSS for a fade-in effect on page load

Can CSS transitions be used to allow a text paragraph to fade-in on page load?

I really like how it looked on http://dotmailapp.com/ and would love to use a similar effect using CSS. The domain has since been purchased and no longer has the effect mentioned. An archived copy can be viewed on the Wayback Machine.

Illustration

Having this markup:

<div id="test">
    <p>?This is a test</p>
</div>??????????????????????????????????????????????????????

With the following CSS rule:

#test p {
    opacity: 0;
    margin-top: 25px;
    font-size: 21px;
    text-align: center;
    -webkit-transition: opacity 2s ease-in;
    -moz-transition: opacity 2s ease-in;
    -o-transition: opacity 2s ease-in;
    -ms-transition: opacity 2s ease-in;
    transition: opacity 2s ease-in;
}?

How can the transition be triggered on load?

This question is related to css css-transitions opacity

The answer is


Method 1:

If you are looking for a self-invoking transition then you should use CSS 3 Animations. They aren't supported either, but this is exactly the kind of thing they were made for.

CSS

#test p {
    margin-top: 25px;
    font-size: 21px;
    text-align: center;

    -webkit-animation: fadein 2s; /* Safari, Chrome and Opera > 12.1 */
       -moz-animation: fadein 2s; /* Firefox < 16 */
        -ms-animation: fadein 2s; /* Internet Explorer */
         -o-animation: fadein 2s; /* Opera < 12.1 */
            animation: fadein 2s;
}

@keyframes fadein {
    from { opacity: 0; }
    to   { opacity: 1; }
}

/* Firefox < 16 */
@-moz-keyframes fadein {
    from { opacity: 0; }
    to   { opacity: 1; }
}

/* Safari, Chrome and Opera > 12.1 */
@-webkit-keyframes fadein {
    from { opacity: 0; }
    to   { opacity: 1; }
}

/* Internet Explorer */
@-ms-keyframes fadein {
    from { opacity: 0; }
    to   { opacity: 1; }
}

/* Opera < 12.1 */
@-o-keyframes fadein {
    from { opacity: 0; }
    to   { opacity: 1; }
}

Demo

Browser Support

All modern browsers and Internet Explorer 10 (and later): http://caniuse.com/#feat=css-animation


Method 2:

Alternatively, you can use jQuery (or plain JavaScript; see the third code block) to change the class on load:

jQuery

$("#test p").addClass("load");?

CSS

#test p {
    opacity: 0;
    font-size: 21px;
    margin-top: 25px;
    text-align: center;

    -webkit-transition: opacity 2s ease-in;
       -moz-transition: opacity 2s ease-in;
        -ms-transition: opacity 2s ease-in;
         -o-transition: opacity 2s ease-in;
            transition: opacity 2s ease-in;
}

#test p.load {
    opacity: 1;
}

Plain JavaScript (not in the demo)

document.getElementById("test").children[0].className += " load";

Demo

Browser Support

All modern browsers and Internet Explorer 10 (and later): http://caniuse.com/#feat=css-transitions


Method 3:

Or, you can use the method that .Mail uses:

jQuery

$("#test p").delay(1000).animate({ opacity: 1 }, 700);?

CSS

#test p {
    opacity: 0;
    font-size: 21px;
    margin-top: 25px;
    text-align: center;
}

Demo

Browser Support

jQuery 1.x: All modern browsers and Internet Explorer 6 (and later): http://jquery.com/browser-support/
jQuery 2.x: All modern browsers and Internet Explorer 9 (and later): http://jquery.com/browser-support/

This method is the most cross-compatible as the target browser does not need to support CSS 3 transitions or animations.


In response to @A.M.K's question about how to do transitions without jQuery. A very simple example I threw together. If I had time to think this through some more, I might be able to eliminate the JavaScript code altogether:

<style>
    body {
        background-color: red;
        transition: background-color 2s ease-in;
    }
</style>

<script>
    window.onload = function() {
        document.body.style.backgroundColor = '#00f';
    }
</script>

<body>
    <p>test</p>
</body>

Looking forward to Web Animations in 2020.

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async function moveToPosition(el, durationInMs) {
  return new Promise((resolve) => {
    const animation = el.animate([{
        opacity: '0'
      },
      {
        transform: `translateY(${el.getBoundingClientRect().top}px)`
      },
    ], {
      duration: durationInMs,
      easing: 'ease-in',
      iterations: 1,
      direction: 'normal',
      fill: 'forwards',
      delay: 0,
      endDelay: 0
    });
    animation.onfinish = () => resolve();
  });
}

async function fadeIn(el, durationInMs) {
  return new Promise((resolve) => {
    const animation = el.animate([{
        opacity: '0'
      },
      {
        opacity: '0.5',
        offset: 0.5
      },
      {
        opacity: '1',
        offset: 1
      }
    ], {
      duration: durationInMs,
      easing: 'linear',
      iterations: 1,
      direction: 'normal',
      fill: 'forwards',
      delay: 0,
      endDelay: 0
    });
    animation.onfinish = () => resolve();
  });
}

async function fadeInSections() {
  for (const section of document.getElementsByTagName('section')) {
    await fadeIn(section, 200);
  }
}

window.addEventListener('load', async() => {
  await moveToPosition(document.getElementById('headerContent'), 500);
  await fadeInSections();
  await fadeIn(document.getElementsByTagName('footer')[0], 200);
});
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body,
html {
  height: 100vh;
}

header {
  height: 20%;
}

.text-center {
  text-align: center;
}

.leading-none {
  line-height: 1;
}

.leading-3 {
  line-height: .75rem;
}

.leading-2 {
  line-height: .25rem;
}

.bg-black {
  background-color: rgba(0, 0, 0, 1);
}

.bg-gray-50 {
  background-color: rgba(249, 250, 251, 1);
}

.pt-12 {
  padding-top: 3rem;
}

.pt-2 {
  padding-top: 0.5rem;
}

.text-lightGray {
  color: lightGray;
}

.container {
  display: flex;
  /* or inline-flex */
  justify-content: space-between;
}

.container section {
  padding: 0.5rem;
}

.opacity-0 {
  opacity: 0;
}
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<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="utf-8" />
  <link rel="icon" href="/favicon.ico" />
  <meta name="viewport" content="width=device-width, initial-scale=1" />
  <meta name="description" content="Web site created using create-snowpack-app" />
  <link rel="stylesheet" type="text/css" href="./assets/syles/index.css" />
</head>

<body>
  <header class="bg-gray-50">
    <div id="headerContent">
      <h1 class="text-center leading-none pt-2 leading-2">Hello</h1>
      <p class="text-center leading-2"><i>Ipsum lipmsum emus tiris mism</i></p>
    </div>
  </header>
  <div class="container">
    <section class="opacity-0">
      <h2 class="text-center"><i>ipsum 1</i></h2>
      <p>Cras purus ante, dictum non ultricies eu, dapibus non tellus. Nam et ipsum nec nunc vestibulum efficitur nec nec magna. Proin sodales ex et finibus congue</p>
    </section>
    <section class="opacity-0">
      <h2 class="text-center"><i>ipsum 2</i></h2>
      <p>Cras purus ante, dictum non ultricies eu, dapibus non tellus. Nam et ipsum nec nunc vestibulum efficitur nec nec magna. Proin sodales ex et finibus congue</p>
    </section>

    <section class="opacity-0">
      <h2 class="text-center"><i>ipsum 3</i></h2>
      <p>Cras purus ante, dictum non ultricies eu, dapibus non tellus. Nam et ipsum nec nunc vestibulum efficitur nec nec magna. Proin sodales ex et finibus congue</p>
    </section>
  </div>
  <footer class="opacity-0">
    <h1 class="text-center leading-3 text-lightGray"><i>dictum non ultricies eu, dapibus non tellus</i></h1>
    <p class="text-center leading-3"><i>Ipsum lipmsum emus tiris mism</i></p>
  </footer>
</body>

</html>
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You can use the onload="" HTML attribute and use JavaScript to adjust the opacity style of your element.

Leave your CSS as you proposed. Edit your HTML code to:

<body onload="document.getElementById(test).style.opacity='1'">
    <div id="test">
        <p>?This is a test</p>
    </div>
</body>

This also works to fade-in the complete page when finished loading:

HTML:

<body onload="document.body.style.opacity='1'">
</body>

CSS:

body{ 
    opacity: 0;
    transition: opacity 2s;
    -webkit-transition: opacity 2s; /* Safari */
}

Check the W3Schools website: transitions and an article for changing styles with JavaScript.


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