Лупа на JQuery

<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script>

<div class="magnify">
   
  <!--Это увеличительное стекло, которое будет содержать оригинальный / большой вариант -->
  <div class="large"></div>
   
  <!-- Это небольшое изображение -->
  <img class="small" src="http://thecodeplayer.com/uploads/media/iphone.jpg" width="200"/>
   
</div>

<script>
$(document).ready(function(){

  var native_width = 0;
  var native_height = 0;

  //Now the mousemove function
  $(".magnify").mousemove(function(e){
  //When the user hovers on the image, the script will first calculate
  //the native dimensions if they don't exist. Only after the native dimensions
  //are available, the script will show the zoomed version.
  if(!native_width && !native_height)
  {
  //This will create a new image object with the same image as that in .small
  //We cannot directly get the dimensions from .small because of the  
  //width specified to 200px in the html. To get the actual dimensions we have
  //created this image object.
  var image_object = new Image();
  image_object.src = $(".small").attr("src");
   
  //This code is wrapped in the .load function which is important.
  //width and height of the object would return 0 if accessed before  
  //the image gets loaded.
  native_width = image_object.width;
  native_height = image_object.height;
  }
  else
  {
  //x/y coordinates of the mouse
  //This is the position of .magnify with respect to the document.
  var magnify_offset = $(this).offset();
  //We will deduct the positions of .magnify from the mouse positions with
  //respect to the document to get the mouse positions with respect to the  
  //container(.magnify)
  var mx = e.pageX - magnify_offset.left;
  var my = e.pageY - magnify_offset.top;
   
  //Finally the code to fade out the glass if the mouse is outside the container
  if(mx < $(this).width() && my < $(this).height() && mx > 0 && my > 0)
  {
  $(".large").fadeIn(200);
  }
  else
  {
  $(".large").fadeOut(200);
  }
  if($(".large").is(":visible"))
  {
  //The background position of .large will be changed according to the position
  //of the mouse over the .small image. So we will get the ratio of the pixel
  //under the mouse pointer with respect to the image and use that to position the  
  //large image inside the magnifying glass
  var rx = Math.round(mx/$(".small").width()*native_width - $(".large").width()/2)*-1;
  var ry = Math.round(my/$(".small").height()*native_height - $(".large").height()/2)*-1;
  var bgp = rx + "px " + ry + "px";
   
  //Time to move the magnifying glass with the mouse
  var px = mx - $(".large").width()/2;
  var py = my - $(".large").height()/2;
  //Now the glass moves with the mouse
  //The logic is to deduct half of the glass's width and height from the  
  //mouse coordinates to place it with its center at the mouse coordinates
   
  //If you hover on the image now, you should see the magnifying glass in action
  $(".large").css({left: px, top: py, backgroundPosition: bgp});
  }
  }
  })
})

</script>

<style>
/*Some CSS*/
* {margin: 0; padding: 0;}
.magnify {width: 500px; margin: 50px auto; position: relative; cursor: none}

/*Lets create the magnifying glass*/
.large {
  width: 175px; height: 175px;
  position: absolute;
  border-radius: 100%;
   
  /*Multiple box shadows to achieve the glass effect*/
  box-shadow: 0 0 0 7px rgba(255, 255, 255, 0.85),  
  0 0 7px 7px rgba(0, 0, 0, 0.25),  
  inset 0 0 40px 2px rgba(0, 0, 0, 0.25);
   
  /*Lets load up the large image first*/
  background: url('iphone.jpg') no-repeat;
   
  /*hide the glass by default*/
  display: none;
}

/*To solve overlap bug at the edges during magnification*/
.small { display: block; }
</style>