.fadeTo()

Categories: Effects > Fading

.fadeTo( duration, opacity [, complete ] )Returns: jQuery

Description: Adjust the opacity of the matched elements.

The .fadeTo() method animates the opacity of the matched elements. It is similar to the .fadeIn() method but that method unhides the element and always fades to 100% opacity.

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, the default duration of 400 milliseconds is used. Unlike the other effect methods, .fadeTo() requires that duration be explicitly specified.

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:

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<div id="clickme">
  Click here
</div>
<img id="book" src="book.png" alt="" width="100" height="123">
// With the element initially shown, we can dim it slowly:
$( "#clickme" ).click(function() {
  $( "#book" ).fadeTo( "slow" , 0.5, function() {
    // Animation complete.
  });
});
Figure 1 - Illustration of the fadeTo() effect

With duration set to 0, this method just changes the opacity CSS property, so .fadeTo( 0, opacity ) is the same as .css( "opacity", opacity ).

Additional Notes:

  • All jQuery effects, including .fadeTo(), can be turned off globally by setting jQuery.fx.off = true, which effectively sets the duration to 0. For more information, see jQuery.fx.off.

Examples:

Animates first paragraph to fade to an opacity of 0.33 (33%, about one third visible), completing the animation within 600 milliseconds.

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<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>fadeTo demo</title>
  <script src="jquery-1.10.2.js"></script>
</head>
<body>
 
<p>
Click this paragraph to see it fade.
</p>
 
<p>
Compare to this one that won't fade.
</p>
 
<script>
$( "p:first" ).click(function() {
  $( this ).fadeTo( "slow", 0.33 );
});
</script>
 
</body>
</html>

Demo:

Fade div to a random opacity on each click, completing the animation within 200 milliseconds.

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<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>fadeTo demo</title>
  <style>
  p {
    width: 80px;
    margin: 0;
    padding: 5px;
  }
  div {
    width: 40px;
    height: 40px;
    position: absolute;
  }
  #one {
    top: 0;
    left: 0;
    background: #f00;
  }
  #two {
    top: 20px;
    left: 20px;
    background: #0f0;
  }
  #three {
    top: 40px;
    left:40px;
    background:#00f;
  }
  </style>
  <script src="jquery-1.10.2.js"></script>
</head>
<body>
 
<p>And this is the library that John built...</p>
 
<div id="one"></div>
<div id="two"></div>
<div id="three"></div>
 
<script>
$( "div" ).click(function() {
  $( this ).fadeTo( "fast", Math.random() );
});
</script>
 
</body>
</html>

Demo:

Find the right answer! The fade will take 250 milliseconds and change various styles when it completes.

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<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>fadeTo demo</title>
  <style>
  div, p {
    width: 80px;
    height: 40px;
    top: 0;
    margin: 0;
    position: absolute;
    padding-top: 8px;
  }
  p {
    background: #fcc;
    text-align: center;
  }
  div {
    background: blue;
  }
  </style>
  <script src="jquery-1.10.2.js"></script>
</head>
<body>
 
<p>Wrong</p>
<div></div>
<p>Wrong</p>
<div></div>
<p>Right!</p>
<div></div>
 
<script>
var getPos = function( n ) {
  return (Math.floor( n ) * 90) + "px";
};
$( "p" ).each(function( n ) {
  var r = Math.floor( Math.random() * 3 );
  var tmp = $( this ).text();
  $( this ).text( $( "p:eq(" + r + ")" ).text() );
  $( "p:eq(" + r + ")" ).text( tmp );
  $( this ).css( "left", getPos( n ) );
});
$( "div" )
  .each(function( n ) {
    $( this ).css( "left", getPos( n ) );
  })
  .css( "cursor", "pointer" )
  .click( function() {
    $( this ).fadeTo( 250, 0.25, function() {
      $( this )
        .css( "cursor", "" )
        .prev()
          .css({
            "font-weight": "bolder",
            "font-style": "italic"
          });
    });
  });
</script>
 
</body>
</html>

Demo: