如何向此 JQuery 图像交换添加简单的淡入淡出动画?

How do I add a simple fade animation to this JQuery image swap?

我有以下结构和 JQuery 函数(基于 this):

var sourceSwap = function () {
    var $this = $(this);
    var newSource = $this.data('alt-src');
    $this.data('alt-src', $this.attr('src'));
    $this.attr('src', newSource);
}

$(function() {
    $('img[data-alt-src]').each(function() { 
        new Image().src = $(this).data('alt-src'); 
    }).hover(sourceSwap, sourceSwap);
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<img src="https://images.pexels.com/photos/414612/pexels-photo-414612.jpeg?auto=compress&cs=tinysrgb&dpr=1&w=500" data-alt-src="https://images.pexels.com/photos/237018/pexels-photo-237018.jpeg?auto=compress&cs=tinysrgb&dpr=1&w=500">

我该如何为它添加一个简单的淡入淡出动画?目前只是瞬间转换

您可以使用 CSS

执行如下操作

#cf {
  position:relative;
  height:281px;
  width:450px;
  margin:0 auto;
}

#cf img {
  position:absolute;
  left:0;
  -webkit-transition: opacity 1s ease-in-out;
  -moz-transition: opacity 1s ease-in-out;
  -o-transition: opacity 1s ease-in-out;
  transition: opacity 1s ease-in-out;
}

#cf img.top:hover {
  opacity:0;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div id="cf">
<img class="bottom" src="https://images.pexels.com/photos/414612/pexels-photo-414612.jpeg?auto=compress&cs=tinysrgb&dpr=1&w=500">

<img  class="top" src="https://images.pexels.com/photos/237018/pexels-photo-237018.jpeg?auto=compress&cs=tinysrgb&dpr=1&w=500" >
</div>

使用.fadeTo()当图片源改变时生效。根据您的要求增加或减少数量。

var sourceSwap = function() {
  var $this = $(this);
  var newSource = $this.data('alt-src');
  $this.data('alt-src', $this.attr('src'));
  $this.fadeTo(1000, 0.15, function() {
    $this.attr("src", newSource);
  }).fadeTo(200, 1);
}

$(function() {
  $('img[data-alt-src]').each(function() {
    new Image().src = $(this).data('alt-src');
  }).hover(sourceSwap, sourceSwap);
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<img class="xyz" data-alt-src="http://cdn1.iconfinder.com/data/icons/fatcow/32/accept.png" src="http://cdn1.iconfinder.com/data/icons/fatcow/32/cancel.png" />
<br/>
<img class="xyz" data-alt-src="http://cdn1.iconfinder.com/data/icons/fatcow/32/accept.png" src="http://cdn1.iconfinder.com/data/icons/fatcow/32/cancel.png" />
<br/>
<img class="xyz" data-alt-src="http://cdn1.iconfinder.com/data/icons/fatcow/32/accept.png" src="http://cdn1.iconfinder.com/data/icons/fatcow/32/cancel.png" />