add onTagExists and fix events

README.markdown

@@ -224,6 +224,14 @@ The function receives an empty event, and an object with a `tag` property.
 
 Behaves the same as **beforeTagRemoved** except that it fires after the tag has been removed from the DOM.
 
+### onTagExists (function, Callback)
+
+Triggered when attempting to add a tag that has already been added in the widget. The callback receives an empty event,
+and an object containing the properties `existingTag` and `duringInitialization`, since technically you could try to preload
+duplicate tags during the widget initialization.
+
+If the **allowDuplicates** option is enabled, this will not be triggered.
+
 ### onTagClicked (function, Callback)
 
 Can be used to add custom behaviour when the tag is clicked.

examples.html

@@ -94,6 +94,9 @@
                 },
                 onTagClicked: function(evt, ui) {
                     addEvent('onTagClicked: ' + eventTags.tagit('tagLabel', ui.tag));
+                },
+                onTagExists: function(evt, ui) {
+                    addEvent('onTagExists: ' + eventTags.tagit('tagLabel', ui.existingTag));
                 }
             });
 

js/tag-it.js

@@ -173,7 +173,7 @@
                     if (target.hasClass('tagit-label')) {
                         var tag = target.closest('.tagit-choice');
                         if (!tag.hasClass('removed')) {
-                            that._trigger('onTagClicked', e, tag);
+                            that._trigger('onTagClicked', e, {tag: tag});
                         }
                     } else {
                         // Sets the focus() to the input field, if the user
@@ -352,16 +352,20 @@
             this.tagInput.autocomplete('search', '');
         },
 
-        _isNew: function(value) {
+        _existingTag: function(value) {
             var that = this;
-            var isNew = true;
+            var tag = null;
             this._tags().each(function(i) {
                 if (that._formatStr(value) == that._formatStr(that.tagLabel(this))) {
-                    isNew = false;
+                    tag = $(this);
                     return false;
                 }
             });
-            return isNew;
+            return tag;
+        },
+
+        _isNew: function(value) {
+            return !this._existingTag(value);
         },
 
         _formatStr: function(str) {
@@ -376,7 +380,12 @@
 
             value = $.trim(value);
 
-            if (!this.allowDuplicates && (!this._isNew(value) || value === '')) {
+            if (value === '') {
+                return false;
+            }
+
+            if (!this.allowDuplicates && !this._isNew(value)) {
+                this._trigger('onTagExists', null, {existingTag: this._existingTag(value), duringInitialization: duringInitialization});
                 return false;
             }