JQ_返回顶部

$(function(){
$('#goto_top_btn').click(function() {
var s = $(window).scrollTop(),h = $(window).height();
if (s > h * 2) {
$('html, body').scrollTop(0);
} else {
$('html,body').animate({scrollTop: '0px'}, 300);
}
});
});

<div class="fix-layout">
<div id="_returnTop_layout_inner" class="gb-operation-area">
<a id="goto_top_btn" class="gb-operation-button return-top" href="javascript:;">
<i class="gb-operation-icon" title="返回顶部"></i>
<span class="gb-operation-text">顶部</span>
</a>
<a id="" class="gb-operation-button report" href="javascript:;" style="display: block;">
<i class="gb-operation-icon" title="举报"></i>
<span class="gb-operation-text">举报</span>
</a>
</div>
</div>