Readable byte streamsBaseline · Newly available
A ReadableStream constructed with { type: "bytes" } reads bytes from a stream without making extra copies, improving efficiency for streams of large chunks. Also known as BYOB or bring your own buffer.
Works in the latest version of every major browser, but older devices may not support it yet. Baseline since Mar 24, 2026.
Browser support
DesktopChrome
1–88Not supported
89+Supportedsince Mar 2, 2021
Current: 155Edge
12–88Not supported
89+Supportedsince Mar 4, 2021
Current: 154Firefox
1–101Not supported
102+Supportedsince Jun 28, 2022
Current: 157Safari
1–26.3Not supported
26.4+Supportedsince Mar 24, 2026
Current: 27MobileChrome Android
18–88Not supported
89+Supportedsince Mar 2, 2021
Current: 155Firefox Android
4–101Not supported
102+Supportedsince Jun 28, 2022
Current: 157Safari iOS
1–26.3Not supported
26.4+Supportedsince Mar 24, 2026
Current: 27How to use
Every current browser supports this, but it only became Baseline on Mar 24, 2026. Use it as a progressive enhancement, or keep a fallback if you support older devices.
Example
Full syntax and examples are on MDN: ReadableByteStreamController.
Feature detection
JS · check before using
if ("ReadableByteStreamController" in globalThis) {
// ReadableByteStreamController is available
} else {
// load a polyfill or use a fallback
}Sub-features
Support for each part of the feature (18). The overall table above shows when the whole feature works.