Fix #12685. Handle inconsistent opacity for ie < 9. Close gh-1005.

1 files changed, 6 insertions, 4 deletions

diff --git a/src/css.js b/src/css.js
index 6dd13efdf..1723223e5 100644
--- a/src/css.js
+++ b/src/css.js
@@ -1,6 +1,6 @@
 var curCSS, iframe, iframeDoc,
 	ralpha = /alpha\([^)]*\)/i,
-	ropacity = /opacity=([^)]*)/,
+	ropacity = /opacity\s*=\s*([^)]*)/,
 	rposition = /^(top|right|bottom|left)$/,
 	// swappable if display is none or starts with table except "table", "table-cell", or "table-caption"
 	// see here for display values: https://developer.mozilla.org/en-US/docs/CSS/display
@@ -535,7 +535,9 @@ if ( !jQuery.support.opacity ) {
 			style.zoom = 1;
 
 			// if setting opacity to 1, and no other filters exist - attempt to remove filter attribute #6652
-			if ( value >= 1 && jQuery.trim( filter.replace( ralpha, "" ) ) === "" &&
+			// if value === "", then remove inline opacity #12685
+			if ( ( value >= 1 || value === "" ) &&
+                jQuery.trim( filter.replace( ralpha, "" ) ) === "" &&
 				style.removeAttribute ) {
 
 				// Setting style.filter to null, "" & " " still leave "filter:" in the cssText
@@ -543,8 +545,8 @@ if ( !jQuery.support.opacity ) {
 				// style.removeAttribute is IE Only, but so apparently is this code path...
 				style.removeAttribute( "filter" );
 
-				// if there there is no filter style applied in a css rule, we are done
-				if ( currentStyle && !currentStyle.filter ) {
+				// if there is no filter style applied in a css rule or unset inline opacity, we are done
+				if ( value === "" || currentStyle && !currentStyle.filter ) {
 					return;
 				}
 			}