$.fn.popImg = function() {
  //your code goes here
}

;(function($,window,document,undefined){
  $.fn.popImg = function() {
   //your code goes here
  }
})(jQuery,window,document);

;(function($,window,document,undefined){
 $.fn.popImg = function(){

   //创建弹出层
   var $layer = $("<div>").css({
    position:'fixed',
    left:0,
    right:0,
    top:0,
    bottom:0,
    width:'100%',
    height:'100%',
    zIndex:9999999,
    display:'none',
    background: "#000",
    opacity:'0.6'
   });

   //复制点击的图片，获得图片的宽高以及位置
   var cloneImg = function($targetImg){
     var cloneW = $targetImg.width(),
       cloneH = $targetImg.height(),
       left = $targetImg.offset().left,
       top = $targetImg.offset().top;

     return $targetImg.clone().css({
       position:'fixed',
       width:cloneW,
       height:cloneH,
       left:left,
       top:top,
       zIndex:10000000
     });
   };

   //让复制的图片居中显示
   var centerImg = function($cloneImg){
     var dW = $(window).width();
     var dH = $(window).height();
     $cloneImg.css('cursor','zoom-out').attr('clone-bigImg',true);
     var img = new Image();
     img.onload = function(){
      $cloneImg.stop().animate({
         width: this.width,
        height: this.height,
        left: (dW - this.width) / 2,
        top: (dH - this.height) / 2
      },300);
     }
     img.src = $cloneImg.attr('src');
   };

   this.each(function(){
     $(this).css('cursor','zoom-in').on('click',function(){
       var $body = $("body");
       $layer.appendTo($body);
       $layer.fadeIn(300);
       var $c = cloneImg($(this));
       $c.appendTo($body);
       centerImg($c);
     });
   });

  var timer = null;
  $(window).on("resize", function(){
   $("img[clone-bigImg]").each(function(){
    var $this = $(this);
    timer && clearTimeout(timer);
    timer = setTimeout(function(){
     centerImg($this);
    }, 10);
   });
  });

  $(window).on("click keydown", function(evt){
   if(evt.type == "keydown" && evt.keyCode === 27) {
    $layer.fadeOut(300);
    $("img[clone-bigImg]").remove();
   }
   var $this = $(evt.target);
   if($this.attr("clone-bigImg")){
    $layer.fadeOut(300);
    $("img[clone-bigImg]").remove();
   }
  });
 }
})(jQuery,window,document);