$(window).scroll(function(){

    var scrollHeight = $(document).height(); //文档高度

    var scrollTop = $(this).scrollTop(); //滚动条卷去高度

    var windowHeight = $(this).height(); // 窗口高度

    // console.log(scrollHeight, scrollTop, windowHeight)

    if(scrollHeight - scrollTop - windowHeight < 100 ){

        console.log("到底了");

        //ajax渲染页面

    }

});

jQuery(function($){

    var topicBoxTopHeight = jQuery('#topicBox').offset().top;

    var topicBoxTopHeight_show = 1

    $(window).scroll(function(event){

        if($(this).scrollTop() > topicBoxTopHeight-$(window).height()-200 && topicBoxTopHeight_show==1){

            topicBoxTopHeight_show=0;

            topicBoxFn();

        }

    });

})