检查元素在div中是否可见 [英] Check if element is visible in div
问题描述
< div>
< li>< / li>
< li>< / li>
< li>< / li>
< li>< / li>
< li>< / li>
...
< / div>
通常当用户在窗口内滚动时,一些< li>
进入溢出状态,将被隐藏。我知道我可以用这个jQuery插件检查一个元素是否在屏幕的视口中: http:// www .appelsiini.net / projects / viewport
我只需要这个功能,但不是整个屏幕,而是只在一个div上。所以我可以在元素不可见的时候更新一些文本。
需要一些帮助,请提前致谢!
(function($){
$ .belowthefold = function(lookIn,元素,设置){
var fold = $(lookIn).height()+ $(lookIn).scrollTop();
return $(elements).filter(function(){
返回fold< = $(this).offset()。top - settings.threshold;
});
};
$ .abovethetop = function(lookIn,elements ,设置){
var top = $(lookIn).scrollTop();
return $(elements).filter(function(){
return top> = $(this)。 offset()。top + $(this).height() - settings.threshold;
});
};
$ .rightofscreen = function(lookIn,elements,设置){
var fold = $(lookIn) .width()+ $(lookIn).scrollLeft();
return $(elements).filter(function(){
return fold <= $(this).offset()。left - settings.threshold;
});
};
$ .leftofscreen = function(lookIn,elements,settings){
var left = $(lookIn).scrollLeft();
return $(elements).filter(function(){
return left> = $(this).offset()。left + $(this).width() - settings.threshold;
});
};
})(jQuery);
使用这样的HTML:
< div id =lookInMe>
< div class =peek>< / div>
< div class =peek>< / div>
[...]
< / div>
像这样调用它:
<$ p $ (#lookInMe,.peek,{threshold:0})。text(Below);
$ .abovethetop(#lookInMe,.peek,{threshold:0}).text(Above);
。.leftofscreen(#lookInMe,.peek,{threshold:0})。text(Left);
$ .rightofscreen(#lookInMe,.peek,{threshold:0}).text(Right);
http://jsfiddle.net/daCrosby/vhF7x/1/
I have a div with many li's inside.
<div>
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
...
</div>
Typically when the user is scrolling inside the window, some <li>
's get into the overflow and will be hidden. I know I can check if an element is in the viewport of the screen with this jQuery Plugin: http://www.appelsiini.net/projects/viewport
I would just need this functionality, but not for the whole screen, but on a single div only. So I could update some text when elements aren't visible.
Need some help, Thanks in advance!
This is a very good answer, but here's a modified version of the Viewport plugin you mentioned.
(function($) {
$.belowthefold = function(lookIn, elements, settings) {
var fold = $(lookIn).height() + $(lookIn).scrollTop();
return $(elements).filter(function(){
return fold <= $(this).offset().top - settings.threshold;
});
};
$.abovethetop = function(lookIn, elements, settings) {
var top = $(lookIn).scrollTop();
return $(elements).filter(function(){
return top >= $(this).offset().top + $(this).height() - settings.threshold;
});
};
$.rightofscreen = function(lookIn, elements, settings) {
var fold = $(lookIn).width() + $(lookIn).scrollLeft();
return $(elements).filter(function(){
return fold <= $(this).offset().left - settings.threshold;
});
};
$.leftofscreen = function(lookIn, elements, settings) {
var left = $(lookIn).scrollLeft();
return $(elements).filter(function(){
return left >= $(this).offset().left + $(this).width() - settings.threshold;
});
};
})(jQuery);
With HTML like this:
<div id="lookInMe">
<div class="peek"></div>
<div class="peek"></div>
[ ... ]
</div>
Call it like this:
$.belowthefold("#lookInMe", ".peek", {threshold : 0}).text("Below");
$.abovethetop("#lookInMe", ".peek", {threshold : 0}).text("Above");
$.leftofscreen("#lookInMe", ".peek", {threshold : 0}).text("Left");
$.rightofscreen("#lookInMe", ".peek", {threshold : 0}).text("Right");
http://jsfiddle.net/daCrosby/vhF7x/1/
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