<script>

//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");

}

}

</script>