SharedStorageWorkletGlobalScope: register() method

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

The register() method of the SharedStorageWorkletGlobalScope interface registers an operation defined inside the current worklet module.


register(name, operationCtor)



A string representing the name with which you want to register the operation. When the operation is invoked (say via or WindowSharedStorage.selectURL()), this name is used to identify the operation you want to run.


A string representing the class name of the operation to be registered. This is the class constructor that is invoked when the operation is run.

Return value

None (undefined).



Thrown if:

  • An operation has already been registered with the specified name.
  • The operationCtor is not a valid constructor.
  • The class does not contain a valid run() method.
  • The worklet module has not been added with SharedStorageWorklet.addModule().


// ab-testing-worklet.js
class SelectURLOperation {
  async run(urls, data) {
    // Read the user's experiment group from shared storage
    const experimentGroup = await this.sharedStorage.get("ab-testing-group");

    // Return the group number
    return experimentGroup;

register("ab-testing", SelectURLOperation);

See the Shared Storage API landing page for a walkthrough of this example and for links to other examples.

Note: It is possible to define and register multiple operations in the same shared storage worklet module script with different names; see SharedStorageOperation for an example.


Shared Storage API
# dom-sharedstorageworkletglobalscope-register

Browser compatibility

BCD tables only load in the browser

See also