原生javascript、js判断滚动到浏览器底部触发事件

window.onscroll = function(){
        //变量scrollTop是滚动条滚动时，距离顶部的距离
        var scrollTop = document.documentElement.scrollTop||document.body.scrollTop;
        //变量windowHeight是可视区的高度
        var windowHeight = document.documentElement.clientHeight || document.body.clientHeight;
        //变量scrollHeight是滚动条的总高度
        var scrollHeight = document.documentElement.scrollHeight||document.body.scrollHeight;
               //滚动条到底部的条件
            if(scrollTop+windowHeight==scrollHeight){
                
                console.log("距顶部"+scrollTop+"可视区高度"+windowHeight+"滚动条总高度"+scrollHeight);
             }   
        }