jquery.lazyload.js 图片延迟加载

 jQuery页面图片伴随滚动条逐渐显示 
根据实际应用可以进行相应的修改

// 天涯版  (function(jQuery) {        jQuery.fn.lazyload = function(options) {          var settings = {              threshold    : 0,              failurelimit : 0,              event        : "scroll",              effect       : "show",              container    : window          };                            if(options) {              jQuery.extend(settings, options);          }            /* Fire one scroll event per scroll. Not one scroll event per image. */          var elements = this;          if ("scroll" == settings.event) {              jQuery(settings.container).bind("scroll", function(event) {                                    var counter = 0;                  elements.each(function() {                      if (jQuery.abovethetop(this, settings)) {                              /* Nothing. */                      } else if (!jQuery.belowthefold(this, settings)) {                              jQuery(this).trigger("appear");                      } else {                          if (counter++ > settings.failurelimit) {                              return false;                          }                      }                  });                  /* Remove image from array so it is not looped next time. */                  var temp = jQuery.grep(elements, function(element) {                      return !element.loaded;                  });                  elements = jQuery(temp);              });          }                    this.each(function() {              var self = this;                            /* Save original only if it is not defined in HTML. */              if (undefined != jQuery(self).attr("original")){      self.loaded = false;        /* When appear is triggered load original image. */      jQuery(self).one("appear", function() {       if (!this.loaded) {        jQuery("<img />")         .bind("load", function() {          jQuery(self)           .hide()           .removeAttr("height")           .attr("src", jQuery(self).attr("original"))           [settings.effect](settings.effectspeed);          self.loaded = true;         })         .attr("src", jQuery(self).attr("original"));       };      });     }          });                    /* Force initial check if images should appear. */          jQuery(settings.container).trigger(settings.event);                    return this;      };        /* Convenience methods in jQuery namespace.           */      /* Use as  jQuery.belowthefold(element, {threshold : 100, container : window}) */      function checkshow(){          }         jQuery.belowthefold = function(element, settings) {          if (settings.container === undefined || settings.container === window) {              var fold = jQuery(window).height()*2 + jQuery(window).scrollTop();          } else {              var fold = jQuery(settings.container).offset().top + jQuery(settings.container).height()*2;          }            return fold <= jQuery(element).offset().top - settings.threshold;        };         jQuery.abovethetop = function(element, settings) {          if (settings.container === undefined || settings.container === window) {              var fold = jQuery(window).scrollTop();          } else {              var fold = jQuery(settings.container).offset().top;          }          return fold >= jQuery(element).offset().top + settings.threshold  + jQuery(element).height();      };      /* Custom selectors for your convenience.   */      /* Use as jQuery("img:below-the-fold").something() */        jQuery.extend(jQuery.expr[':'], {          "below-the-fold" : "jQuery.belowthefold(a, {threshold : 0, container: window})",          "above-the-fold" : "!jQuery.belowthefold(a, {threshold : 0, container: window})"      });        })(jQuery);      jQuery("#pContentDiv .post img[original]").lazyload({   effect:"fadeIn"  });