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Diffstat (limited to 'docs/content/error/ngRepeat/dupes.ngdoc')
| -rw-r--r-- | docs/content/error/ngRepeat/dupes.ngdoc | 20 |
1 files changed, 19 insertions, 1 deletions
diff --git a/docs/content/error/ngRepeat/dupes.ngdoc b/docs/content/error/ngRepeat/dupes.ngdoc index eb25ec67..42d4c77a 100644 --- a/docs/content/error/ngRepeat/dupes.ngdoc +++ b/docs/content/error/ngRepeat/dupes.ngdoc @@ -1,4 +1,22 @@ @ngdoc error @name ngRepeat:dupes -@fullName Duplicate Repeater Key +@fullName Duplicate Key in Repeater @description + +Occurs if there are duplicate keys in an {@link api/ng.directive:ngRepeat ngRepeat} expression. Duplicate keys are banned because AngularJS uses keys to associate DOM nodes with items. + +By default, collections are keyed by reference which is desirable for most common models but can be problematic for primitive types that are interned (share references). + +For example the issue can be triggered by this *invalid* code: + +``` +<div ng-repeat="value in [4, 4]"></div> +``` + +To resolve this error either ensure that the items in the collection have unique identity of use the `track by` syntax to specify how to track the association between models and DOM. + +To resolve the example above can be resolved by using `track by $index`, which will cause the items to be keyed by their position in the array instead of their value: + +``` +<div ng-repeat="value in [4, 4] track by $index"></div> +``` |