.fadeIn()

.fadeIn( [ duration ], [ callback ] ) Returns: jQuery

Description: Display the matched elements by fading them to opaque.

  • version added: 1.0.fadeIn( [ duration ], [ callback ] )

    durationA string or number determining how long the animation will run.

    callbackA function to call once the animation is complete.

The .fadeIn() method animates the opacity of the matched elements.

Durations are given in milliseconds; higher values indicate slower animations, not faster ones. The strings 'fast' and 'slow' can be supplied to indicate durations of 200 and 600 milliseconds, respectively. If any other string is supplied, or if the duration parameter is omitted, the default duration of 400 milliseconds is used.

If supplied, the callback is fired once the animation is complete. This can be useful for stringing different animations together in sequence. The callback is not sent any arguments, but this is set to the DOM element being animated. If multiple elements are animated, it is important to note that the callback is executed once per matched element, not once for the animation as a whole.

We can animate any element, such as a simple image:

<div id="clickme">
      Click here
    </div>
    <img id="book" src="book.png" alt="" width="100" height="123" />
    With the element initially hidden, we can show it slowly:
    $('#clickme').click(function() {
      $('#book').fadeIn('slow', function() {
        // Animation complete
      });
    });

Examples:

Example: Animates hidden divs to fade in one by one, completing each animation within 600 milliseconds.

<!DOCTYPE html>
<html>
<head>
  <style>
    span { color:red; cursor:pointer; }
    div { margin:3px; width:80px; display:none;
      height:80px; float:left; }
      div#one { background:#f00; }
      div#two { background:#0f0; }
      div#three { background:#00f; }
    </style>
  <script src="http://code.jquery.com/jquery-latest.js"></script>
</head>
<body>
	<span>Click here...</span>

    <div id="one"></div>
    <div id="two"></div>
    <div id="three"></div>
<script>
      $(document.body).click(function () {
        $("div:hidden:first").fadeIn("slow");
      });
    </script>
</body>
</html>

Demo:

Example: Fades a red block in over the text. Once the animation is done, it quickly fades in more text on top.

<!DOCTYPE html>
<html>
<head>
  <style>
      p { position:relative; width:400px; height:90px; }
      div { position:absolute; width:400px; height:65px; 
        font-size:36px; text-align:center; 
        color:yellow; background:red;
        padding-top:25px; 
        top:0; left:0; display:none; }
        span { display:none; }
      </style>
  <script src="http://code.jquery.com/jquery-latest.js"></script>
</head>
<body>
	<p>
        Let it be known that the party of the first part
        and the party of the second part are henceforth
        and hereto directed to assess the allegations
        for factual correctness... (<a href="#">click!</a>)
        <div><span>CENSORED!</span></div>

      </p>
<script>
        $("a").click(function () {
          $("div").fadeIn(3000, function () {
            $("span").fadeIn(100);
          });
          return false;
        }); 

      </script>
</body>
</html>

Demo: