picLazyLoad 实现图片延时加载(包含背景图片)

如下所示： 

;(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

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

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