html代码：

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<style>
.dis_none{
       display : none;
}
</style>
<body>
       <section class='page1'>
		<img src="" data-src='./img.png'>
		<img src="" data-src='./img.png'>
		<img src="" data-src='./img.png'>
	</section>
	<section class='page2 dis_none'>
		<img src="" data-src='./img.png'>
		<img src="" data-src='./img.png'>
		<img src="" data-src='./img.png'>
	</section>
</body>

javascript 代码：

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var lazyLoad=function(obj,fun){
 var load = function (obj){
     var loadThis=this;
     this.imgArr=[];
     this.num=0;
     $(obj+" img").each(function(){
         if($(this).attr("data-src")){
             loadThis.imgArr[loadThis.imgArr.length]=$(this).attr("data-src");
             $(this).attr("src",loadThis.imgArr[loadThis.imgArr.length-1]);
             $(this).attr("data-src","");
         }
     });
     if(typeof fun=="function"){
         this.callBack(fun)
     }
  };
  load.prototype.callBack=function(fun){
      var loadThis=this,len = loadThis.imgArr.length-1;
      for(var i=0; i<this.imgArr.length;i++){
          var img = new Image();
          img.src = this.imgArr[i];
          img.onload=function(){
              if(loadThis.num<len){
                  loadThis.num++;
              }else {
                  fun()
              }
          }
          img.onerror=function(){
              if(loadThis.num<len){
                  loadThis.num++;
              }else {
                  fun()
              }
          }
      }
  };
  return new load(obj,fun)
};

ex:

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lazyLoad('.page1', function(){
  lazyLoad('.page2', function(){
    $('.page1').addClass('dis_none');
    $('.page2').removeClass('dis_none');
  });
});

目前版本 依赖zepto库。迟点更新无依赖版本。