我已经找到了一些使用 jQuery 检查滚动条位置的好方法,但我想知道你是否能区分用户向上或向下滚动了?
<script type='text/javascript'>
$(function(){
var CurrentScroll = 0;
$(window).scroll(function(event){
var NextScroll = $(this).scrollTop();
if (NextScroll > CurrentScroll){
//write the codes related to down-ward scrolling here
}
else {
//write the codes related to upward-scrolling here
}
CurrentScroll = NextScroll; //Updates current scroll position
});
});
last_scroll_position
,当您滚动时,如果last_scroll_position - current_position > 0
,则用户向上滚动,如果小于0,则向下滚动。last_scroll_position
和 current_position
相同,则结果将为 0
,此时如何找到?????? - rynhelast_scroll_position - current_position == 0
,那么用户根本没有滚动。 - Gabi Purcarulast_scroll_position < current_position //往下滚动
反之亦然。减去一个数再进行比较是否有一定的原因,而不是直接比较? - user1816910var mousewheelevt = (/Firefox/i.test(navigator.userAgent)) ? "DOMMouseScroll" : "mousewheel" //FF doesn't recognize mousewheel as of FF3.x
$('#yourDiv').bind(mousewheelevt, function(e){
var evt = window.event || e //equalize event object
evt = evt.originalEvent ? evt.originalEvent : evt; //convert to originalEvent if possible
var delta = evt.detail ? evt.detail*(-40) : evt.wheelDelta //check for detail first, because it is used by Opera and FF
if(delta > 0) {
//scroll up
}
else{
//scroll down
}
});
这种方法也适用于具有overflow:hidden
的
我已经在FireFox,IE和Chrome上成功测试过了。
纯JavaScript的示例:
var f = (function(){
var oldPos = window.scrollY;
function fu(e) {
var newPos = window.scrollY;
if (newPos>oldPos) {
console.log('down');
} else if(newPos<oldPos) {
console.log('up');
} else {
console.log('same');
}
oldPos = newPos;
}
return fu;
})();
window.addEventListener('scroll',f);
滚动事件在火狐浏览器中表现得有些奇怪(由于平滑滚动会触发很多次),但它确实有效。
注意:实际上,滚动事件会在拖动滚动条、使用光标键或鼠标滚轮时被触发。
//creates an element to print the scroll position
$("<p id='test'>").appendTo("body").css({
padding: "5px 7px",
background: "#e9e9e9",
position: "fixed",
bottom: "15px",
left: "35px"
});
//binds the "scroll" event
$(window).scroll(function (e) {
var target = e.currentTarget,
$self = $(target),
scrollTop = window.pageYOffset || target.scrollTop,
lastScrollTop = $self.data("lastScrollTop") || 0,
scrollHeight = target.scrollHeight || document.body.scrollHeight,
scrollText = "";
if (scrollTop > lastScrollTop) {
scrollText = "<b>scroll down</b>";
} else {
scrollText = "<b>scroll up</b>";
}
$("#test").html(scrollText +
"<br>innerHeight: " + $self.innerHeight() +
"<br>scrollHeight: " + scrollHeight +
"<br>scrollTop: " + scrollTop +
"<br>lastScrollTop: " + lastScrollTop);
if (scrollHeight - scrollTop === $self.innerHeight()) {
console.log("► End of scroll");
}
//saves the current scrollTop
$self.data("lastScrollTop", scrollTop);
});
你也可以参考MDN提供的 滚轮事件 文档,获得更多有关滚轮事件的信息。
注意: 滚轮事件仅在使用鼠标滚轮时触发;使用方向键或拖动滚动条不能触发该事件。
我阅读了这个文档和示例:在不同浏览器中监听此事件
并通过与 FF、IE、Chrome 和 Safari 的一些测试,得出以下代码片段:
//creates an element to print the scroll position
$("<p id='test'>").appendTo("body").css({
padding: "5px 7px",
background: "#e9e9e9",
position: "fixed",
bottom: "15px",
left: "15px"
});
//attach the "wheel" event if it is supported, otherwise "mousewheel" event is used
$("html").on(("onwheel" in document.createElement("div") ? "wheel" : "mousewheel"), function (e) {
var evt = e.originalEvent || e;
//this is what really matters
var deltaY = evt.deltaY || (-1 / 40 * evt.wheelDelta), //wheel || mousewheel
scrollTop = $(this).scrollTop() || $("body").scrollTop(), //fix safari
scrollText = "";
if (deltaY > 0) {
scrollText = "<b>scroll down</b>";
} else {
scrollText = "<b>scroll up</b>";
}
//console.log("Event: ", evt);
$("#test").html(scrollText +
"<br>clientHeight: " + this.clientHeight +
"<br>scrollHeight: " + this.scrollHeight +
"<br>scrollTop: " + scrollTop +
"<br>deltaY: " + deltaY);
});
有一种简单的方法可以做到这一点,而不需要任何全局变量。MouseWheel事件有一个明确指定滚动方向的属性。以下是如何使用它:
$("#scroll_div").bind("mousewheel",function(ev) {
var curScrollLeft = $(this).scrollLeft();
$(this).scrollLeft(curScrollLeft + Math.round(ev.originalEvent.wheelDelta));
});