Improve remove event bindings for classes options.

jquery/jquery-ui@ef2e9ba

js/vendor/jquery.ui.widget.js

@@ -509,11 +509,29 @@
         classes: this.options.classes || {}
       }, options );
 
+      function bindRemoveEvent() {
+        options.element.each( function( _, element ) {
+          var isTracked = $.map( that.classesElementLookup, function( elements ) {
+            return elements;
+          } )
+            .some( function( elements ) {
+              return elements.is( element );
+            } );
+
+          if ( !isTracked ) {
+            that._on( $( element ), {
+              remove: "_untrackClassesElement"
+            } );
+          }
+        } );
+      }
+
       function processClassString( classes, checkOption ) {
         var current, i;
         for ( i = 0; i < classes.length; i++ ) {
           current = that.classesElementLookup[ classes[ i ] ] || $();
           if ( options.add ) {
+            bindRemoveEvent();
             current = $( $.unique( current.get().concat( options.element.get() ) ) );
           } else {
             current = $( current.not( options.element ).get() );
@@ -526,10 +544,6 @@
         }
       }
 
-      this._on( options.element, {
-        "remove": "_untrackClassesElement"
-      } );
-
       if ( options.keys ) {
         processClassString( options.keys.match( /\S+/g ) || [], true );
       }
@@ -547,6 +561,8 @@
           that.classesElementLookup[ key ] = $( value.not( event.target ).get() );
         }
       } );
+
+      this._off( $( event.target ) );
     },
 
     _removeClass: function( element, keys, extra ) {
@@ -627,7 +643,7 @@
     _off: function( element, eventName ) {
       eventName = ( eventName || "" ).split( " " ).join( this.eventNamespace + " " ) +
         this.eventNamespace;
-      element.off( eventName ).off( eventName );
+      element.off( eventName );
 
       // Clear the stack to avoid memory leaks (#10056)
       this.bindings = $( this.bindings.not( element ).get() );