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Returns: jQueryjQuery .animate( Map properties, Map options )

描述:执行一组CSS属性的自定义动画。
  • version added: 1.0
  • .animate( Map properties, String,Number duration, String easing, Function complete )
  • properties json对象,设定动画走向的一组CSS属性效果。
    duration 字符串或数字,用来规定动画的达到目标效果所需的时间,即渐变的速度。
    easing 字符串,说明使用何种动画函数来过渡。
    complete 函数,动画结束时调用的函数。
  • version added: 1.0
  • .animate( Map properties, Map options )
  • properties json对象,设定动画走向的一组CSS属性效果。
    options json对象,传递给动画方法的一组额外的选项。键值支持:
    • duration: 字符串或数字,用来规定动画的达到目标效果所需的时间,即渐变的速度。
    • easing:字符串,说明使用何种动画函数来过渡。
    • complete: 函数,动画结束时调用的函数。
    • step:函数,动画执行完每一步后调用的函数。
    • queue: bool,说明是否将影响队列中的动画。false,动画将马上开始。 As of jQuery 1.7, queue也可以接受字符串参数,在这种情况下,动画被添加到该字符串所表示的队列。
    • specialEasing:json对象,json格式的一个或多个CSS属性和它们相应的缓动函数(added 1.4).

.animate() 方法使我们能够创建任何数字CSS属性的动画效果。 仅仅一组json格式的CSS属性是必须的。该函数的CSS属性跟.css()方法接受的参数基本一致,除了属性的范围是更严格。

动画属性和值

All animated properties should be animated to a single numeric value, except as noted below; most properties that are non-numeric cannot be animated using basic jQuery functionality (For example, width, height, or left can be animated but background-color cannot be, unless the jQuery.Color() plugin is used). Property values are treated as a number of pixels unless otherwise specified. The units em and % can be specified where applicable.

In addition to style properties, some non-style properties such as scrollTop and scrollLeft, as well as custom properties, can be animated.

Shorthand CSS properties (e.g. margin, background, border) are not supported. For example, if you want to retrieve the rendered margin, use: $(elem).css('marginTop') and $(elem).css('marginRight'), and so on.

In addition to numeric values, each property can take the strings 'show', 'hide', and 'toggle'. These shortcuts allow for custom hiding and showing animations that take into account the display type of the element.

Animated properties can also be relative. If a value is supplied with a leading += or -= sequence of characters, then the target value is computed by adding or subtracting the given number from the current value of the property.

Note: Unlike shorthand animation methods such as .slideDown() and .fadeIn(), the .animate() method does not make hidden elements visible as part of the effect. For example, given $('someElement').hide().animate({height:'20px'}, 500), the animation will run, but the element will remain hidden.

Duration

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.

Complete Function

If supplied, the complete callback function 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, the callback is executed once per matched element, not once for the animation as a whole.

Basic Usage

To 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"
  style="position: relative; left: 10px;" />

To animate the opacity, left offset, and height of the image simultaneously:

$('#clickme').click(function() {
  $('#book').animate({
    opacity: 0.25,
    left: '+=50',
    height: 'toggle'
  }, 5000, function() {
    // Animation complete.
  });
});

Note that the target value of the height property is 'toggle'. Since the image was visible before, the animation shrinks the height to 0 to hide it. A second click then reverses this transition:

The opacity of the image is already at its target value, so this property is not animated by the second click. Since the target value for left is a relative value, the image moves even farther to the right during this second animation.

Directional properties (top, right, bottom, left) have no discernible effect on elements if their position style property is static, which it is by default.

Note: The jQuery UI project extends the .animate() method by allowing some non-numeric styles such as colors to be animated. The project also includes mechanisms for specifying animations through CSS classes rather than individual attributes.

Note: if attempting to animate an element with a height or width of 0px, where contents of the element are visible due to overflow, jQuery may clip this overflow during animation. By fixing the dimensions of the original element being hidden however, it is possible to ensure that the animation runs smoothly. A clearfix can be used to automatically fix the dimensions of your main element without the need to set this manually.

Step Function

The second version of .animate() provides a step option — a callback function that is fired at each step of the animation. This function is useful for enabling custom animation types or altering the animation as it is occurring. It accepts two arguments (now and fx), and this is set to the DOM element being animated.

  • now: the numeric value of the property being animated at each step
  • fx: a reference to the jQuery.fx prototype object, which contains a number of properties such as elem for the animated element, start and end for the first and last value of the animated property, respectively, and prop for the property being animated.

Note that the step function is called for each animated property on each animated element. For example, given two list items, the step function fires four times at each step of the animation:

$('li').animate({
  opacity: .5,
  height: '50%'
},
{
  step: function(now, fx) {
    var data = fx.elem.id + ' ' + fx.prop + ': ' + now;
    $('body').append('<div>' + data + '</div>');
  }
});

Easing

The remaining parameter of .animate() is a string naming an easing function to use. An easing function specifies the speed at which the animation progresses at different points within the animation. The only easing implementations in the jQuery library are the default, called swing, and one that progresses at a constant pace, called linear. More easing functions are available with the use of plug-ins, most notably the jQuery UI suite.

Per-property Easing

As of jQuery version 1.4, you can set per-property easing functions within a single .animate() call. In the first version of .animate(), each property can take an array as its value: The first member of the array is the CSS property and the second member is an easing function. If a per-property easing function is not defined for a particular property, it uses the value of the .animate() method's optional easing argument. If the easing argument is not defined, the default swing function is used.

For example, to simultaneously animate the width and height with the swing easing function and the opacity with the linear easing function:

$('#clickme').click(function() {
  $('#book').animate({
    width: ['toggle', 'swing'],
    height: ['toggle', 'swing'],
    opacity: 'toggle'
  }, 5000, 'linear', function() {
      $(this).after('<div>Animation complete.</div>');
  });
});

In the second version of .animate(), the options map can include the specialEasing property, which is itself a map of CSS properties and their corresponding easing functions. For example, to simultaneously animate the width using the linear easing function and the height using the easeOutBounce easing function:

$('#clickme').click(function() {
  $('#book').animate({
    width: 'toggle',
    height: 'toggle'
  }, {
    duration: 5000,
    specialEasing: {
      width: 'linear',
      height: 'easeOutBounce'
    },
    complete: function() {
      $(this).after('<div>Animation complete.</div>');
    }
  });
});

As previously noted, a plugin is required for the easeOutBounce function.

Examples:

Example:

Click the button to animate the div with a number of different properties.
<!DOCTYPE html>
<html>
<head>
  <script src="../jquery.min.js"></script>
  <style>div {
background-color:#bca;
width:100px;
border:1px solid green;
}</style>
</head>
<body>
  <button id="go">&raquo; Run</button>

<div id="block">Hello!</div>
  <script>/* Using multiple unit types within one animation. */

$("#go").click(function(){
  $("#block").animate({
    width: "70%",
    opacity: 0.4,
    marginLeft: "0.6in",
    fontSize: "3em",
    borderWidth: "10px"
  }, 1500 );
});</script>
</body>
</html>

Demo:

Example:

Animates a div's left property with a relative value. Click several times on the buttons to see the relative animations queued up.
<!DOCTYPE html>
<html>
<head>
  <script src="../jquery.min.js"></script>
  <style>div {
  position:absolute;
  background-color:#abc;
  left:50px;
  width:90px;
  height:90px;
  margin:5px;
}</style>
</head>
<body>
  <button id="left">&laquo;</button> <button id="right">&raquo;</button>
<div class="block"></div>

  <script>$("#right").click(function(){
  $(".block").animate({"left": "+=50px"}, "slow");
});

$("#left").click(function(){
  $(".block").animate({"left": "-=50px"}, "slow");
});</script>
</body>
</html>

Demo:

Example:

The first button shows how an unqueued animation works. It expands the div out to 90% width while the font-size is increasing. Once the font-size change is complete, the border animation will begin. The second button starts a traditional chained animation, where each animation will start once the previous animation on the element has completed.
<!DOCTYPE html>
<html>
<head>
  <script src="../jquery.min.js"></script>
  <style>div {
  background-color:#bca;
  width:200px;
  height:1.1em;
  text-align:center;
  border:2px solid green;
  margin:3px;
  font-size:14px;
}
button {
  font-size:14px;
}</style>
</head>
<body>
  <button id="go1">&raquo; Animate Block1</button>
<button id="go2">&raquo; Animate Block2</button>
<button id="go3">&raquo; Animate Both</button>

<button id="go4">&raquo; Reset</button>
<div id="block1">Block1</div>
<div id="block2">Block2</div>
  <script>$( "#go1" ).click(function(){
  $( "#block1" ).animate( { width: "90%" }, { queue: false, duration: 3000 })
     .animate({ fontSize: "24px" }, 1500 )
     .animate({ borderRightWidth: "15px" }, 1500 );
});

$( "#go2" ).click(function(){
  $( "#block2" ).animate({ width: "90%" }, 1000 )
     .animate({ fontSize: "24px" }, 1000 )
     .animate({ borderLeftWidth: "15px" }, 1000 );
});

$( "#go3" ).click(function(){
  $( "#go1" ).add( "#go2" ).click();
});

$( "#go4" ).click(function(){
  $( "div" ).css({ width: "", fontSize: "", borderWidth: "" });
});</script>
</body>
</html>

Demo:

Example:

Animates the first div's left property and synchronizes the remaining divs, using the step function to set their left properties at each stage of the animation.
<!DOCTYPE html>
<html>
<head>
  <script src="../jquery.min.js"></script>
  <style>div {
   position: relative;
   background-color: #abc;
   width: 40px;
   height: 40px;
   float: left;
   margin: 5px;
}</style>
</head>
<body>
  
<p><button id="go">Run »</button></p>
<div class="block"></div> <div class="block"></div>
<div class="block"></div> <div class="block"></div>
<div class="block"></div> <div class="block"></div>

  <script>$( "#go" ).click(function(){
  $( ".block:first" ).animate({
    left: 100
  }, {
    duration: 1000,
    step: function( now, fx ){
      $( ".block:gt(0)" ).css( "left", now );
    }
  });
});</script>
</body>
</html>

Demo:

Example:

Animates all paragraphs to toggle both height and opacity, completing the animation within 600 milliseconds.
$( "p" ).animate({
  "height": "toggle", "opacity": "toggle"
}, "slow" );

Example:

Animates all paragraph to a left style of 50 and opacity of 1 (opaque, visible), completing the animation within 500 milliseconds.
$( "p" ).animate({
  "left": "50", "opacity": 1
}, 500 );

Example:

An example of using an 'easing' function to provide a different style of animation. This will only work if you have a plugin that provides this easing function. Note, this code will do nothing unless the paragraph element is hidden.
$( "p" ).animate({
  "opacity": "show"
}, "slow", "easein" );

Example:

Animates all paragraphs to toggle both height and opacity, completing the animation within 600 milliseconds.
$( "p" ).animate({
  "height": "toggle", "opacity": "toggle"
}, { duration: "slow" });

Example:

Animates all paragraph to a left style of 50 and opacity of 1 (opaque, visible), completing the animation within 500 milliseconds. It also will do it outside the queue, meaning it will automatically start without waiting for its turn.
$( "p" ).animate({
  left: "50px", opacity: 1
}, { duration: 500, queue: false });

Example:

An example of using an 'easing' function to provide a different style of animation. This will only work if you have a plugin that provides this easing function.
$( "p" ).animate({
  "opacity": "show"
}, { "duration": "slow", "easing": "easein" });

Example:

An example of using a callback function. The first argument is an array of CSS properties, the second specifies that the animation should take 1000 milliseconds to complete, the third states the easing type, and the fourth argument is an anonymous callback function.
$( "p" ).animate({
  height:200, width:400, opacity: .5
}, 1000, "linear", function(){ alert("all done"); });