dropload上拉加载更多因footer高度导致内容无法触底导致加载异常问题

代码如下：

		<link rel="stylesheet" href="dist/dropload.css">
		...
			<div class="content">
					<div class="lists">
					      ...
					</div>
			</div>		

		<script src="dist/dropload.min.js"></script>
		<script>
			$(function() {
				var counter = 0;
				// 每页展示4个
				var num = 1;
				var pageStart = 0,
					pageEnd = 0;
				// dropload
				$('.content').dropload({
					scrollArea: window,
					domDown: {
						domClass: 'dropload-down',
						domRefresh: '<div class="dropload-refresh">↑上拉加载更多</div>',
						domLoad: '<div class="dropload-load"><span class="loading"></span>加载中...</div>',
						domNoData: '<div class="dropload-noData">暂无数据</div>'
					},
					loadDownFn: function(me) {
						$.ajax({
							type: 'GET',
							url: 'json/more.json',
							dataType: 'json',
							success: function(data) {
								console.log(data);
								var result = '';
								counter++;
								pageEnd = num * counter;
								pageStart = pageEnd - num;
								for (var i = pageStart; i < pageEnd; i++) {
									result =
										'<div role="tabpanel" class="tab-pane active" id="tabMobile"><div class="row caseItem"><div class="col-md-3 col-sm-3 col-xs-12 iphone-image"><img src="' +
										data.lists[i].pic + '" alt=""/></div><div class="col-md-9 col-sm-9 col-xs-12"><h5>' + data.lists[i].title +
										'</h5><p>' + data.lists[i].text + '</p></div></div></div>';
									if ((i + 1) >= data.lists.length) {
										// 锁定
										me.lock();
										// 无数据
										me.noData();
										break;
									}
								}
								// 为了测试，延迟1秒加载
								setTimeout(function() {
									$('.lists').append(result);
									// 每次数据加载完，必须重置
									me.resetload();
								}, 500);
							},
							error: function(xhr, type) {
								alert('Ajax error!');
								// 即使加载出错，也得重置
								me.resetload();
							}
						});
					},
					threshold: 350
				});
			});
		</script>

threshold这个属性是提前加载距离，修改这个数值就可以。