移动端 H5 页面懒加载优化

function load() {
    console.log('loading');    }
$(window).scroll(function(){
    var scrollTop = $(window).scrollTop();        var windowHeight = $(window).height();        var scrollHeight = $(document).height();        var distance = scrollHeight - scrollTop - windowHeight;        if(distance < 200 ){            load();            }    });

    $(window).scroll(function(){            if (timeoutId) {                    clearTimeout(timeoutId);                    }                timeoutId = setTimeout(function() {                    // var scrollTop = $(this).scrollTop();
            var scrollTop = $(window).scrollTop;                        var windowHeight = $(window).height();                        var scrollHeight = $(document).height();                        var distance = scrollHeight - scrollTop - windowHeight;             if(distance < 200 ){                            lazyLoad();                            }                    }, 60)            });

var loading = false;
function append() {        console.log('append element to document');    }
function load() {
    loading = true;        $.ajax({            url: 'api.xxx.com'
    }).done(function(res) {            append();                loading = false;            })    }
$(window).scroll(function(){
    var scrollTop = $(window).scrollTop();        var windowHeight = $(window).height();        var scrollHeight = $(document).height();        var distance = scrollHeight - scrollTop - windowHeight;        if(distance < 200 && !loading ){            load();            }    });