学步园

function lazyload(option) {
    var settings = {
 defObj: null,
 defHeight: 0
    };
   
    settings = $.extend(settings, option || {});
    var defHeight = settings.defHeight;
    var defObj = (typeof settings.defObj == "object") ? settings.defObj.find("img") : $(settings.defObj).find("img");
    var pageTop = function() {
 return document.documentElement.clientHeight + Math.max(document.documentElement.scrollTop, document.body.scrollTop) - settings.defHeight;
    };
   
    var imgLoad = function() {
 defObj.each(function() {
     if ($(this).offset().top <= pageTop()) {
         var src2 = $(this).attr("src2");
  
  if (src2) {
      $(this).attr("src", src2).removeAttr("src2");
  }
            }
 });
    };
   
    imgLoad();
    $(window).bind("scroll", function() {
        imgLoad();
    });
}

lazyload({
    defObj:".w1"
});