js 滚动到底部自动刷新

 
//获取滚动条当前的位置 
function getScrollTop() { 
var scrollTop = 0; 
if (document.documentElement && document.documentElement.scrollTop) { 
scrollTop = document.documentElement.scrollTop; 
} 
else if (document.body) { 
scrollTop = document.body.scrollTop; 
} 
return scrollTop; 
} 

//获取当前可是范围的高度 
function getClientHeight() { 
var clientHeight = 0; 
if (document.body.clientHeight && document.documentElement.clientHeight) { 
clientHeight = Math.min(document.body.clientHeight, document.documentElement.clientHeight); 
} 
else { 
clientHeight = Math.max(document.body.clientHeight, document.documentElement.clientHeight); 
} 
return clientHeight; 
} 

//获取文档完整的高度 
function getScrollHeight() { 
return Math.max(document.body.scrollHeight, document.documentElement.scrollHeight); 
} 

window.onscroll = function () {
if (getScrollTop() + getClientHeight() == getScrollHeight()) {
alert("到达底部");
}
}