WorkletSharedStorage: remainingBudget() 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 remainingBudget() method of the WorkletSharedStorage interface returns the remaining navigation budget for the current origin.

The navigation budget is the number of entropy bits permitted inside a <fencedframe> due to the WindowSharedStorage.selectURL() calls per origin every 24 hours. This is not the same as the number of navigations; rather, it is based on the number of potential navigations in each call. Each time a selectURL() navigation occurs, the corresponding origin's budget decreases by the logarithm (base 2) of the number of URL choices.

Navigation budget is a mechanism designed to limit the rate of leakage of cross-site data to the destination pages navigated to in fenced frames.

Syntax

js
remainingBudget()

Parameters

None.

Return value

A Promise that fulfills with a number representing the remaining navigation budget.

Exceptions

TypeError

Thrown if the worklet module has not yet been added with addModule() or if the calling site does not have the Shared Storage API included in a successful privacy sandbox enrollment process.

Examples

js
// remainingBudget() available inside a shared storage worklet module

async function retrieveBudget() {
  const budget = await this.sharedStorage.remainingBudget();
  console.log(budget);
}

Specifications

Specification
Shared Storage API
# dom-workletsharedstorage-remainingbudget

Browser compatibility

BCD tables only load in the browser

See also