SharedStorage: set() method

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

The set() method of the SharedStorage interface either stores a new key-value pair in the current origin's shared storage or updates an existing one.


set(key, value)
set(key, value, options)



A string representing the key in the key-value pair that you want to add or update.


A string representing the value you want to add or update.

options Optional

An options object containing the following properties:


A boolean value. The value true causes the set operation to abort if a key-value pair with the specified key already exists. The default value false causes the set operation to overwrite the previous value.

Return value

A Promise that fulfills with undefined.


  • The Promise rejects with a TypeError if:
    • The created 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 set() 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.


  .set("ab-testing-group", "0", {
    ignoreIfPresent: true,
  .then(console.log("Set operation completed"));


Shared Storage API
# dom-sharedstorage-set

Browser compatibility

BCD tables only load in the browser

See also