javascript 当窗口顶部到达特定元素时将类添加到 DIV 并在未到达时将其删除
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Add a class to a DIV when top of the window reach a specific element and remove it when not
提问by Farzad Bayan
I have a .navigationin the top of the wrapper.
I want to add it a .fixedclass, when the top of the window reached the .bottomDIV & remove this class when the top of the .bottomis in the window`s scope (it's a toggling between add and remove .fixed class).
我.navigation在包装纸的顶部有一个。我想给它添加一个.fixed类，当窗口顶部到达.bottomDIV时，当顶部在窗口.bottom的范围内时删除这个类（这是在添加和删除 .fixed 类之间切换）。
<div id="wrapper">
<div class="navigation">
<!-- There are some list elements here -->
</div>
<div class="bottom"></div>
</div>
It's what I made, but not work
这是我做的，但不起作用
bottom = $('.bottom');
$(window).scroll(function(){
if ($(this).scrollTop() > bottom){
$('.navigation').addClass('fixed');
}
else{
$('.navigation').removeClass('fixed');
}
});
回答by Labu
var bottom = $('.bottom').offset().top;
var bottom = $('.bottom').offset().top;
That should do it.
那应该这样做。
This compares the offset from the top of the viewport to the window's scrollTop()instead of comparing a whole element.
这将比较从视口顶部到窗口的偏移量，scrollTop()而不是比较整个元素。
