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function lr(overHide, scrollUl, leftBtn, rightBtn, num) {
var doc = document,
overHide = doc.getElementById(overHide),
scrollUl = doc.getElementById(scrollUl),
liArr = scrollUl.getElementsByTagName('li'),
len = liArr.length,
leftBtn = doc.getElementById(leftBtn),
rightBtn = doc.getElementById(rightBtn),
overWidth = overHide.offsetWidth;
scrollUl.style.width = len * num + 'px';
var inWidth = scrollUl.offsetWidth;
function checkBtn(overHide, scrollUl, leftBtn, rightBtn) {//判断左右按钮显示与隐藏
if (overWidth >= inWidth) {//内容不够不需要左右按钮
leftBtn.style.visibility = 'hidden';
rightBtn.style.visibility = 'hidden';
} else if (overHide.scrollLeft == 0) {//右显示左隐藏
leftBtn.style.visibility = 'hidden';
rightBtn.style.visibility = 'visible';
} else if ((overHide.scrollLeft + overWidth) == inWidth) {//左显示右隐藏
leftBtn.style.visibility = 'visible';
rightBtn.style.visibility = 'hidden';
} else if ((overHide.scrollLeft + overWidth) < inWidth && overHide.scrollLeft > 0) {//左右均显示
leftBtn.style.visibility = 'visible';
rightBtn.style.visibility = 'visible';
}
}
checkBtn(overHide, scrollUl, leftBtn, rightBtn);
function stepL(obj, step) {
var n = 0;
function scrollL(obj, step) {
if (n < step) {
obj.scrollLeft += 5;
n += 5;
} else {
clearTimeout(comeon)
}
checkBtn(overHide, scrollUl, leftBtn, rightBtn)
var comeon = setTimeout(function () { scrollL(obj, step) }, 20);
}
scrollL(obj, step);
}
function stepR(obj, step) {
var n = step;
function scrollR(obj, step) {
if (n > 0) {
obj.scrollLeft -= 5;
n -= 5;
} else {
clearTimeout(comeon)
}
checkBtn(overHide, scrollUl, leftBtn, rightBtn)
var comeon = setTimeout(function () { scrollR(obj, step) }, 20);
}
scrollR(obj, step);
}
leftBtn.onclick = function () {
stepR(overHide, num)
}
rightBtn.onclick = function () {
stepL(overHide, num)
}
}
lr('scroll_cont', 'scroll_ul', 's_L', 's_R', 122);
Sys.WebForms.PageRequestManager.getInstance().add_endRequest(lr);