picLazyLoad 图片延时加载，包含背景图片

 /**
  * picLazyLoad 图片延时加载，包含背景图片
  * $(img).picLazyLoad({...})
  * data-original  预加载图片地址
  * alon
  */
 ;(function($){
     $.fn.imgLazyLoad = function(settings){
         var $this = $(this),
             _winScrollTop = 0,
             _winHeight = $(window).height();
         settings = $.extend({
             threshold: 0, // 提前高度加载
             placeholder: 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsQAAA7EAZUrDhsAAAANSURBVBhXYzh8+PB/AAffA0nNPuCLAAAAAElFTkSuQmCC',
             callback:function(){}
         }, settings||{});
         // 执行懒加载图片
         lazyLoadPic();
         // 滚动触发换图
         $(window).on('scroll',function(){
             _winScrollTop = document.documentElement.scrollTop || window.pageYOffset || document.body.scrollTop;
             lazyLoadPic();
         });
         // 懒加载图片
         function lazyLoadPic(){
             $this.each(function(){
                 var $self = $(this);
                 if($self.is('img')){
                     if($self.attr('data-original')){
                         var _offsetTop = $self.offset().top;
                         if((_offsetTop - settings.threshold) <= (_winHeight + _winScrollTop)){
                             $self.attr('src',$self.attr('data-original'));
                             $self.removeAttr('data-original');
                             $self.removeClass('loadH');
                             settings.callback($self);
                         }
                     }
                 }else{
                     if($self.attr('data-original')){// 默认占位图片
                         if($self.css('background-image') == 'none'){
                             $self.css('background-image','url('+settings.placeholder+')');
                         }
                         var _offsetTop = $self.offset().top;
                         if((_offsetTop - settings.threshold) <= (_winHeight + _winScrollTop)){
                             $self.css('background-image','url('+$self.attr('data-original')+')');
                             $self.removeAttr('data-original');
                             settings.callback($self);
                         }
                     }
                 }
             });
         }
     }
 })(Zepto);

调用

1 $('img').imgLazyLoad({callback:function(data){

 })