src/css/var/isHiddenWithinTree.js

define( [
	"../../core",
	"../../core/isAttached"

	// css is assumed
], function( jQuery, isAttached ) {
	"use strict";

	// isHiddenWithinTree reports if an element has a non-"none" display style (inline and/or
	// through the CSS cascade), which is useful in deciding whether or not to make it visible.
	// It differs from the :hidden selector (jQuery.expr.pseudos.hidden) in two important ways:
	// * A hidden ancestor does not force an element to be classified as hidden.
	// * Being disconnected from the document does not force an element to be classified as hidden.
	// These differences improve the behavior of .toggle() et al. when applied to elements that are
	// detached or contained within hidden ancestors (gh-2404, gh-2863).
	return function( elem, el ) {

		// isHiddenWithinTree might be called from jQuery#filter function;
		// in that case, element will be second argument
		elem = el || elem;

		// Inline style trumps all
		return elem.style.display === "none" ||
			elem.style.display === "" &&

			// Otherwise, check computed style
			// Support: Firefox <=43 - 45
			// Disconnected elements can have computed display: none, so first confirm that elem is
			// in the document.
			isAttached( elem ) &&

			jQuery.css( elem, "display" ) === "none";
	};
} );