SharedStorage: append() method

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

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

js
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

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

Specifications

Specification
Shared Storage API
# dom-sharedstorage-append

Browser compatibility

Report problems with this compatibility data on GitHub
desktopmobile
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
append
Experimental

Legend

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Full support
Full support
No support
No support
Experimental. Expect behavior to change in the future.

See also