js 页面图片等元素在普通元素中滚动动态加载技术

/*!
 * 2012-01-13 v1.1 偏移值计算修改 position → offset
 * 2012-09-25 v1.2 增加滚动容器参数, 回调参数
 * 2015-11-17 v1.3 只对显示元素进行处理
*/
(function($) {
	$.fn.scrollLoading = function(options) {
		var defaults = {
			attr: "data-url",
			container: $(window),
			callback: $.noop
		};
		var params = $.extend({}, defaults, options || {});
		params.cache = [];
		$(this).each(function() {
			var node = this.nodeName.toLowerCase(), url = $(this).attr(params["attr"]);
			//重组
			var data = {
				obj: $(this),
				tag: node,
				url: url
			};
			params.cache.push(data);
		});
		
		var callback = function(call) {
			if ($.isFunction(params.callback)) {
				params.callback.call(call.get(0));
			}
		};
		//动态显示数据
		var loading = function() {
			
			var contHeight = params.container.height();
			if ($(window).get(0) === window) {
				contop = $(window).scrollTop();
			} else {
				contop = params.container.offset().top;
			}		
			
			$.each(params.cache, function(i, data) {
				var o = data.obj, tag = data.tag, url = data.url, post, posb;

				if (o) {
					post = o.offset().top - contop, post + o.height();
	
					if (o.is(':visible') && (post >= 0 && post < contHeight) || (posb > 0 && posb <= contHeight)) {
						if (url) {
							//在浏览器窗口内
							if (tag === "img") {
								//图片，改变src
								callback(o.attr("src", url));		
							} else {
								o.load(url, {}, function() {
									callback(o);
								});
							}		
						} else {
							// 无地址，直接触发回调
							callback(o);
						}
						data.obj = null;	
					}
				}
			});	
		};
		
		//事件触发
		//加载完毕即执行
		loading();
		//滚动执行
		params.container.bind("scroll", loading);
	};
})(jQuery);


//实例

<script>
    var tempHTML = "";
    for (var i=1; i<=30; i+=1) {
        if (i == 6) {
            tempHTML += '<div class="zxx_test_list scrollLoading" data-url="loaded.html"><div style="padding:100px 0; text-align:center;"><img src="/study/image/loading.gif" style="margin:0 8px -8px 0;" />加载中...</div></div>';
        } else {
            tempHTML += '<div class="zxx_test_list tc"><img class="scrollLoading" data-url="//image.zhangxinxu.com/image/study/head/s180/'+i+'.jpeg" src="//s1.xiaomishu.com/b/img/pixel.gif" width="180" height="180" style="background:url(/study/image/loading.gif) no-repeat center;" /><br />图片'+i+'(新浪微博提供)</div>';
        }
    }
    tempHTML += '<div class="zxx_test_list tc"><h6>下面藏了一张图片，<a href="javascript:" id="zxxClickBtn">点击显示</a></h6>\
        <div id="zxxShow" style="display:none;">\
           <img class="scrollLoading" width="256" height="191" data-url="//image.zhangxinxu.com/image/study/s/s256/mm1.jpg" />\
        </div></div>';
    document.getElementById("zxxMainCon").innerHTML = tempHTML;
</script>

<script>
    $(function() {
        $(".scrollLoading").scrollLoading({
            container: $("#zxxMainCon"),
            callback: function() {
                this.style.border = "3px solid #a0b3d6";
            }
        });

        //$(".scrollLoading").scrollLoading();
        
    });
</script>