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Comment by RussianCow | Hacker News Reader

Can anyone summarize how this works and the use case for this API?

Edit: Here's a good summary: https://developers.google.com/web/updates/2017/06/budget-api

Basically, this lets you run low-cost background tasks without a confirmation from the user. I really, really don't like this, and I hope that, at the very least, this is easy to disable in all the popular browsers.

Edit 2: The above is not correct; browsers already allow a limited amount of background work to happen, and this API just exposes the budget information to the developer. Thanks for the clarification, swsieber.

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No - it doesn't. Quote:

"This specification does not define how user agents establish or store the amount of current budget. It aims to define an API that exposes sufficient information to make the budget useful for authors, while not restricting the implementation details and heuristics specific to a user agent."

So basically, the Push API and Web Background Synchronization actually do that. This just lets pages programmatically find out what the limits are like.

To make an analogy to localStorage - this api is like being able to query local storage for how much space is available, and how often it gets deleted.

So what you're saying is that browsers already allow limited things like push notifications to happen silently without user consent, and this API just exposes the budget/cost for those actions? I'm not up-to-date on the background APIs that browsers expose, but this quote from the Google doc seems to be at odds with what you're saying, if I understand it correctly:

"The Push Messaging API enables us to send notifications to a user even when the browser is closed. [...] but the API has one important restriction: you must always display a notification for every single push message recieved."

And later:

"The Budget API, is a new API designed to allow developers to perform limited background work without notifying the user, such as silent push or performing a background fetch."

Edit: Reading through the spec more closely, it appears you are correct in that this is already happening on the browser side, and that this API just exposes the budgeting details to the developer. The Google Developer page's wording is just somewhat misleading. Thanks for the clarification.

Push notifications – by spec and by all implementations I'm aware of – must not be sent without explicit user consent: https://w3c.github.io/push-api/#security-and-privacy-conside...

Sorry, when I said "without user consent" I really meant "with the tab closed". :) Brain fart.

> Can anyone summarize how this works and the use case for this API?

Both the parent link and the link you specified clearly outline their use cases. Basically, because of a shift to work that can be done invisibly or without a user's consent in a browser, it's important to allow the user to make an informed consent to processor intensive tasks. This API is a step in that direction.

An additional summary (with sample code!) lies in the explainer document:

https://github.com/WICG/budget-api/blob/gh-pages/README.md

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