Conflicting Information regarding storage onChanged

[erosman]

MDN URL

https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/storage/onChanged

What specific section or headline is this issue about?

changes

What information was incorrect, unhelpful, or incomplete?

Due to extension bug reports, I had to test the output of onChanged and I found out that there are conflicting information on MDN which led to the issue.

storage.onChanged

object. Object describing the change. This object contains properties for all the keys in the storage area included in the storageArea.set call, even if key values are unchanged.

storage.StorageArea.onChanged

object. Object describing the change. This contains one property for each key that changed. The name of the property is the name of the key that changed, and its value is a storage.StorageChange object describing the change to that item.

First one says: "all the keys in the storage area, even if key values are unchanged"
Second one says: "one property for each key that changed."

After further testing both APIs storage.onChanged & storage.sync.onChanged:

• Firefox onChanged returns all the keys in the storage area, even if all values are unchanged
• Chrome onChanged returns only the changed values (event doesn't fire when there is no change)

What did you expect to see?

no conflicting information

Do you have any supporting links, references, or citations?

No response

Do you have anything more you want to share?

See also:

• Bug 1833153: storage.sync should not emit onChanged events for calls that are not resulting into changes to the store data

[rebloor]

@erosman from your testing, did you determine whether the statement that "When this event is triggered by storageArea.set, it's possible to receive a callback when there is no change to the underlying data." is still correct? Do you get a call back with an empty object if there are no changes?

[erosman]

@rebloor After further testing, I had to correct & update the test results.

The issue can now be summarised as:

• Confusing text for the 2 APIs
• Inconsistency between Chrome & Firefox implementations