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

…cond 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;