Intent to Ship: FileAPI: Blob.bytes()

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Chromestatus

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Oct 18, 2025, 10:50:50 AMOct 18
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Contact emails
zees...@gmail.com, zi...@chromium.org

Specification
https://www.w3.org/TR/FileAPI

Design docs
No information provided
https://w3c.github.io/FileAPI/#dom-blob-bytes

Summary
The bytes() method of the Blob interface returns a Promise that resolves with a Uint8Array containing the contents of the blob as an array of bytes.

Blink component
Blink>Storage>FileAPI

Web Feature ID
file

Motivation
Before this change developers could not access an ArrayBuffer directly and had to create a Uint8Array view, and some APIs returned different types which leading to inconsistency. To improve this, design principles have changed[1] in w3c tag side, so the spec was updated[2] accordingly. The new spec removes those hassles, and because WebKit, Firefox and Node.js already support it, bringing it to Chromium will improve interoperability as well. [1] https://github.com/w3ctag/design-principles/issues/463 [2] https://github.com/w3ctag/design-principles/pull/480 [3] https://github.com/w3c/FileAPI/pull/198

Initial public proposal
No information provided

TAG review
No information provided

TAG review status
Not applicable

Risks


Interoperability and Compatibility
Safari 18 and Firefox 128 have already shipped the feature.

Gecko: Shipped/Shipping (https://www.firefox.com/en-US/firefox/128.0/releasenotes)

WebKit: Shipped/Shipping (https://webkit.org/blog/15865/webkit-features-in-safari-18-0)

Web developers: No signals

Other signals:

WebView application risks

Does this intent deprecate or change behavior of existing APIs, such that it has potentially high risk for Android WebView-based applications?

No information provided


Debuggability
No information provided

Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, ChromeOS, Android, and Android WebView)?
Yes
All Blob APIs are exposed and platform-independent, and the bytes() API is also supported on all platforms.

Is this feature fully tested by web-platform-tests?
Yes
https://wpt.fyi/results/FileAPI/Blob-methods-from-detached-frame.html https://wpt.fyi/results/FileAPI/blob/Blob-bytes.any.html https://wpt.fyi/results/FileAPI/blob/Blob-bytes.any.worker.html

Flag name on about://flags
No information provided

Finch feature name
No information provided

Non-finch justification
No information provided

Rollout plan
Will ship enabled for all users

Requires code in //chrome?
False

Estimated milestones

No milestones specified



Anticipated spec changes

Open questions about a feature may be a source of future web compat or interop issues. Please list open issues (e.g. links to known github issues in the project for the feature specification) whose resolution may introduce web compat/interop risk (e.g., changing to naming or structure of the API in a non-backward-compatible way).

No information provided

Link to entry on the Chrome Platform Status
https://chromestatus.com/feature/4830298126417920?gate=5146453756084224

Links to previous Intent discussions
Intent to Prototype: https://groups.google.com/a/chromium.org/d/msgid/blink-dev/688952f5.2b0a0220.35091d.0040.GAE%40google.com


This intent message was generated by Chrome Platform Status.

Mike Taylor

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Oct 20, 2025, 9:46:47 AMOct 20
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Could you please request the Privacy, Security, Enterprise, etc bits in your chromestatus entry?

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Mike Taylor

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Oct 27, 2025, 7:57:01 PM (10 days ago) Oct 27
to zi...@chromium.org, zees...@gmail.com, blink-dev

Thanks for requesting those - LGTM1

Suyeon Ji

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Oct 28, 2025, 1:06:24 AM (10 days ago) Oct 28
to blink-dev, mike...@chromium.org, blink-dev, zi...@chromium.org, Suyeon Ji

Hi,

Thank you so much for your review. I’ve submitted the request on ChromeStatus as you suggested, and I’m now waiting for the privacy and security reviews.

I’ll let you know once I get the results.


Thanks again!

2025년 10월 28일 화요일 오전 8시 57분 1초 UTC+9에 mike...@chromium.org님이 작성:

Daniel Bratell

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Oct 28, 2025, 4:23:30 PM (9 days ago) Oct 28
to Suyeon Ji, blink-dev, mike...@chromium.org, zi...@chromium.org

Philip Jägenstedt

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Oct 28, 2025, 5:32:19 PM (9 days ago) Oct 28
to Daniel Bratell, Suyeon Ji, blink-dev, mike...@chromium.org, zi...@chromium.org
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