function scrollToTop() {
return function(btn, input) {
var flag = false;
var timer;
function autoScroll(input) {
var scrollTop = document.body.scrollTop || document.documentElement.scrollTop;
if (scrollTop !== 0) {
timer = setInterval(function() {
var scrollTop = document.body.scrollTop || document.documentElement.scrollTop;
if (scrollTop === 0) {
clearInterval(timer);
} else {
scrollTop -= (document.body.scrollTop) / 8;
document.documentElement.scrollTop = document.body.scrollTop = (scrollTop < 5 ? scrollTop = 0 : scrollTop);
input.value = scrollTop;
flag = true;
}
}, 50);
}
}
window.onscroll = function() {
if (!flag) {
clearInterval(timer);
}
flag = false;
};
btn.onclick = function() {
autoScroll(input);
};
};
}
看了看14年底写的关于页面滚动的代码,居然还是有让我值得思考才能想明白的问题.顿时觉得进步有限.今天我把曾经的代码做了一个封装.避免了全局变量的出现.代码如上.
使用方法:
window.onload = function() {
var btn = document.getElementsByTagName('button')[0];
var oInput = document.getElementsByTagName('input')[0];
var s = scrollToTop();
s(btn, oInput);
};