SharedStorage: append() method

Deprecated: This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.

Non-standard: This feature is not standardized. We do not recommend using non-standard features in production, as they have limited browser support, and may change or be removed. However, they can be a suitable alternative in specific cases where no standard option exists.

The append() method of the SharedStorage interface appends a string to the value of an existing key-value pair in the current origin's shared storage.

Syntax

append(key, value)

Parameters

key: A string representing the key of the key-value pair to which you want to append a value.
value: A string that you want to append to the existing value of the key-value pair.

Note: If the specified key isn't found in the shared storage, the append() operation is equivalent to set(), that is, a new key-value pair with the specified key is added to the shared storage.

Return value

A Promise that fulfills with undefined.

Exceptions

The Promise rejects with a TypeError if:
- The appended entry was not successfully stored in the database due to shared storage not being available (for example it is disabled using a browser setting).
- key and/or value exceed the browser-defined maximum length.
- The calling site does not have the Shared Storage API included in a successful privacy sandbox enrollment process.
In the case of WorkletSharedStorage, the Promise rejects with a TypeError if the worklet module has not been added with SharedStorageWorklet.addModule().

Note: In the case of WindowSharedStorage, if the append() operation doesn't successfully write to the database for a reason other than shared storage not being available, no error is thrown — the operation still fulfills with undefined.

Examples

window.sharedStorage
  .append("integer-list", ",9")
  .then(() => console.log("Value appended to integer list"));