Content creation is an iterative process. Authoring with efficiency requires being able to see what has changed from one iteration to another. Viewing one page version and then the other is inefficient and prone to error. An author wants to be able to easily compare the current page side-by-side with another version.
The page diff feature allows for the convenient side-by-side comparison of two pages with their differences highlighted.
If you are running a version prior to AEM 6.4.3, the user must have the Modify/Create/Delete permission on the node
/content/versionhistory in order to use the feature.
See Developing and Page Diff for more technical details on this feature.
The side-by-side diff can compare:
See the respective topics on how to start the diff within those contexts.
Regardless of the content being compared, the presentation of the diff remains the same.
For example if comparing versions, the current version is displayed on the left and the previous version is displayed on the right.
The source of both pages is clearly displayed in the header bar at the top of the browser window.
The diff detects changes at the component and HTML level. Items that have been changed are highlighted with different colors.
Note the Changed and Moved colors are the same.
When comparing language copies, highlighting is deactivated since in a translation everything changes and highlighting would be of no benefit.
In order to focus on particular content, you can click on the full screen icon for either “side” of the side-by-side diff to enlarge it to the full browser window.
The selected side will fill the entire window, but the bar will remain at the top allowing you to switch between the two pages.
You can also choose to close the full screen view by clicking the exit full screen icon.
You can exit the side-by-side diff at any time by clicking the Close button in the header.
There are some situations in which the page diff may not detect a difference as expected.
When diffing versions and launches, the diff does not take into account dynamic components such as breadcrumbs, menus, product lists or logos (components that rely on the site structure to render their content).
For versions the diff does not recreate the access control policy and live copy relationships.
If any changes are made to an image such as modifying the alt, title, or src attributes, it will be highlighted in blue as changed. However in some cases the image has a Base64 representation of the src attribute and even if both images look the same they will be marked by the diff as different because of the differing src attributes.
The diff is unable to detect image rotation.
If a page is moved, you can no longer perform a diff with any versions made before the move.
Versions can not be compared to each other. Only the current version can be compared with other versions of the page. The current version is always the version that is highlighted with changes.
For more details about the operation of the page diff mechanism as well as limitations which can affect page diff, please see the developer documentation of this feature.