For .show() with no arguments, only set display of elements in the second loop...

For .show() with no arguments, only set display of elements in the second loop if they don't have style.display already set or if style.display isn't none. Fixes #7315.

src/effects.js

@@ -15,28 +15,39 @@ var elemdisplay = {},
 
 jQuery.fn.extend({
 	show: function( speed, easing, callback ) {
+		var elem, display;
+
 		if ( speed || speed === 0 ) {
 			return this.animate( genFx("show", 3), speed, easing, callback);
+
 		} else {
 			for ( var i = 0, j = this.length; i < j; i++ ) {
+				elem = this[i];
+				display = elem.style.display;
+
 				// Reset the inline display of this element to learn if it is
 				// being hidden by cascaded rules or not
-				if ( !jQuery.data(this[i], "olddisplay") && this[i].style.display === "none" ) {
-					this[i].style.display = "";
+				if ( !jQuery.data(elem, "olddisplay") && display === "none" ) {
+					elem.style.display = "";
 				}
 
 				// Set elements which have been overridden with display: none
 				// in a stylesheet to whatever the default browser style is
 				// for such an element
-				if ( this[i].style.display === "" && jQuery.css( this[i], "display" ) === "none" ) {
-					jQuery.data(this[i], "olddisplay", defaultDisplay(this[i].nodeName));
+				if ( display === "" && jQuery.css( elem, "display" ) === "none" ) {
+					jQuery.data(elem, "olddisplay", defaultDisplay(elem.nodeName));
 				}
 			}
 
 			// Set the display of most of the elements in a second loop
 			// to avoid the constant reflow
 			for ( i = 0; i < j; i++ ) {
-				this[i].style.display = jQuery.data(this[i], "olddisplay") || "";
+				elem = this[i];
+				display = elem.style.display;
+
+				if ( display === "" || display === "none" ) {
+					elem.style.display = jQuery.data(elem, "olddisplay") || "";
+				}
 			}
 
 			return this;

test/unit/effects.js

@@ -6,7 +6,20 @@ test("sanity check", function() {
 });
 
 test("show()", function() {
-	expect(23);
+	expect(26);
+
+	var hiddendiv = jQuery("div.hidden");
+
+	equal(jQuery.css( hiddendiv[0], "display"), "none", "hiddendiv is display: none");
+
+	hiddendiv.css("display", "block");
+	equal(jQuery.css( hiddendiv[0], "display"), "block", "hiddendiv is display: block");
+
+	hiddendiv.show();
+	equal(jQuery.css( hiddendiv[0], "display"), "block", "hiddendiv is display: block");
+
+	hiddendiv.css("display","");
+
 	var pass = true, div = jQuery("#main div");
 	div.show().each(function(){
 		if ( this.style.display == "none" ) pass = false;