highlight the existing tag when attempting to create another one

README.markdown

@@ -18,7 +18,7 @@ First, load [jQuery](http://jquery.com/) (v1.4 or greater), [jQuery UI](http://j
     <script src="https://ajax.googleapis.com/ajax/libs/jqueryui/1.8.12/jquery-ui.min.js" type="text/javascript" charset="utf-8"></script>
     <script src="js/tag-it.js" type="text/javascript" charset="utf-8"></script>
 
-If you're using a custom jQuery UI build, it must contain the Core, Widget, Position, and Autocomplete components. The Effects Core with "Blind" Effect components are optional, but used if available.
+If you're using a custom jQuery UI build, it must contain the Core, Widget, Position, and Autocomplete components. The Effects Core with "Blind" and "Highlight" Effect components are optional, but used if available.
 
 The plugin requires a jQuery UI theme to be present, as well as its own included base CSS file ([jquery.tagit.css](http://github.com/aehlke/tag-it/raw/master/css/jquery.tagit.css)). Here we use the Flick theme as an example:
 
@@ -232,6 +232,8 @@ duplicate tags during the widget initialization.
 
 If the **allowDuplicates** option is enabled, this will not be triggered.
 
+By default it will visually highlight the existing tag, unless you return *false* in your callback.
+
 ### onTagClicked (function, Callback)
 
 Can be used to add custom behaviour when the tag is clicked.

js/tag-it.js

@@ -300,11 +300,11 @@
         },
 
         _lastTag: function() {
-            return this.tagList.children('.tagit-choice:last:not(.removed)');
+            return this.tagList.find('.tagit-choice:last:not(.removed)');
         },
 
         _tags: function() {
-            return this.tagList.children('.tagit-choice:not(.removed)');
+            return this.tagList.find('.tagit-choice:not(.removed)');
         },
 
         assignedTags: function() {
@@ -375,6 +375,10 @@
             return $.trim(str.toLowerCase());
         },
 
+        _effectExists: function(name) {
+            return Boolean($.effects && ($.effects[name] || ($.effects.effect && $.effects.effect[name])));
+        },
+
         createTag: function(value, additionalClass, duringInitialization) {
             var that = this;
 
@@ -385,7 +389,15 @@
             }
 
             if (!this.allowDuplicates && !this._isNew(value)) {
-                this._trigger('onTagExists', null, {existingTag: this._existingTag(value), duringInitialization: duringInitialization});
+                var existingTag = this._existingTag(value);
+                if (this._trigger('onTagExists', null, {
+                    existingTag: existingTag,
+                    duringInitialization: duringInitialization
+                }) !== false) {
+                    if (this._effectExists('highlight')) {
+                        existingTag.effect('highlight');
+                    }
+                }
                 return false;
             }
 
@@ -466,7 +478,7 @@
 
             if (animate) {
                 tag.addClass('removed'); // Excludes this tag from _tags.
-                var hide_args = ($.effects && ($.effects.blind || $.effects.effect.blind)) ? ['blind', {direction: 'horizontal'}, 'fast'] : ['fast'];
+                var hide_args = this._effectExists('blind') ? ['blind', {direction: 'horizontal'}, 'fast'] : ['fast'];
 
                 hide_args.push(function() {
                     tag.remove();