滚动加载图片實現

经常看到些网站滚动时自动加载图片，这样做的好处是，不必一次性加载完所有数据，就可以浏览内容。

查找了些相关资，现作下整理：

1、jQuery滚动加载插件scrollLoading，将其封装做成插件：

jquery.scrollLoading.js

(function($) {
    $.fn.scrollLoading = function(options) {
        var defaults = {
            attr: "data-url"    
        };
        var params = $.extend({}, defaults, options || {});
        params.cache = [];
        $(this).each(function() {
            var node = this.nodeName.toLowerCase(), url = $(this).attr(params["attr"]);
            if (!url) { return; }
            //重组
            var data = {
                obj: $(this),
                tag: node,
                url: url
            };
            params.cache.push(data);
        });
        
       //动态显示数据
        var loading = function() {
            var st = $(window).scrollTop(), sth = st + $(window).height();
            $.each(params.cache, function(i, data) {
                var o = data.obj, tag = data.tag, url = data.url;
                if (o) {
                    post = o.position().top; posb = post + o.height();
                    if ((post > st && post < sth) || (posb > st && posb < sth)) {
                        //在浏览器窗口内
                        if (tag === "img") {
                            //图片，改变src
                            o.attr("src", url);    
                        } else {
                            o.load(url);
                        }    
                        data.obj = null;        
                    }
                }
            });        
            return false;    
        };
        
       //事件触发
        //加载完毕即执行
        loading();
       //滚动执行
        $(window).bind("scroll", loading);
    };
})(jQuery);

 2、scrollLoading使用

<script type="text/javascript" src="../ajax/libs/jquery/1.4.1/jquery.min.js"></script>
<script type="text/javascript" src="../js/jquery.scrollLoading.js"></script>
<script> 
$(function() {
	$(".scrollLoading").scrollLoading();	
});
</script>

 

3、HTML中加载图片代码

<div id="zxxMainCon" class="zxx_main_con">
	<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="http://www.zhangxinxu.com/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="http://image.zhangxinxu.com/image/study/head/s180/'+i+'.jpeg" src="http://www.zhangxinxu.com/study/image/pixel.gif" width="180" height="180" style="background:url(http://www.zhangxinxu.com/study/image/loading.gif) no-repeat center;" /><br />图片'+i+'(新浪微博提供)</div>';
			}
		}
		document.getElementById("zxxMainCon").innerHTML = tempHTML;
	</script>
</div>