I made a new custom :pseudo selector for jQuery to test whether an item has one of the following css properties:
- overflow: [scroll|auto]
- overflow-x: [scroll|auto]
- overflow-y: [scroll|auto]
I wanted to find the closest scrollable parent of another element so I also wrote another little jQuery plugin to find the closest parent with overflow.
This solution probably doesn't perform the best, but it does appear to work. I used it in conjunction with the $.scrollTo plugin. Sometimes I need to know whether an element is inside another scrollable container. In that case I want to scroll the parent scrollable element vs the window.
I probably should have wrapped this up in a single plugin and added the psuedo selector as a part of the plugin, as well as exposing a 'closest' method to find the closest (parent) scrollable container.
Anywho....here it is.
$.isScrollable jQuery plugin:
$.fn.isScrollable = function(){
var elem = $(this);
return (
elem.css('overflow') == 'scroll'
|| elem.css('overflow') == 'auto'
|| elem.css('overflow-x') == 'scroll'
|| elem.css('overflow-x') == 'auto'
|| elem.css('overflow-y') == 'scroll'
|| elem.css('overflow-y') == 'auto'
);
};
$(':scrollable') jQuery pseudo selector:
$.expr[":"].scrollable = function(a) {
var elem = $(a);
return elem.isScrollable();
};
$.scrollableparent() jQuery plugin:
$.fn.scrollableparent = function(){
return $(this).closest(':scrollable') || $(window); //default to $('html') instead?
};
Implementation is pretty simple
//does a specific element have overflow scroll?
var somedivIsScrollable = $(this).isScrollable();
//use :scrollable psuedo selector to find a collection of child scrollable elements
var scrollableChildren = $(this).find(':scrollable');
//use $.scrollableparent to find closest scrollable container
var scrollableparent = $(this).scrollableparent();
UPDATE: I found that Robert Koritnik already came up with a much more powerful :scrollable pseudo selector that will identify the scrollable axes and height of scrollable containers, as a part of his $.scrollintoview() jQuery plugin. scrollintoview plugin
Here is his fancy pseudo selector (props):
$.extend($.expr[":"], {
scrollable: function (element, index, meta, stack) {
var direction = converter[typeof (meta[3]) === "string" && meta[3].toLowerCase()] || converter.both;
var styles = (document.defaultView && document.defaultView.getComputedStyle ? document.defaultView.getComputedStyle(element, null) : element.currentStyle);
var overflow = {
x: scrollValue[styles.overflowX.toLowerCase()] || false,
y: scrollValue[styles.overflowY.toLowerCase()] || false,
isRoot: rootrx.test(element.nodeName)
};
// check if completely unscrollable (exclude HTML element because it's special)
if (!overflow.x && !overflow.y && !overflow.isRoot)
{
return false;
}
var size = {
height: {
scroll: element.scrollHeight,
client: element.clientHeight
},
width: {
scroll: element.scrollWidth,
client: element.clientWidth
},
// check overflow.x/y because iPad (and possibly other tablets) don't dislay scrollbars
scrollableX: function () {
return (overflow.x || overflow.isRoot) && this.width.scroll > this.width.client;
},
scrollableY: function () {
return (overflow.y || overflow.isRoot) && this.height.scroll > this.height.client;
}
};
return direction.y && size.scrollableY() || direction.x && size.scrollableX();
}
});
