ReadableStreamBYOBReader Min Option

concepts

1. BYOB min

   BYOB readers gain a min option — the read resolves only when at least min bytes are filled. Reduces the read-loop tax for sites that want bigger chunks at the cost of latency.

2. Decoder Buffer

   The decoder motivation: side-by-side iteration counts for "loop-and-concat" vs. read(view, {min}) against a stream that emits jagged chunks.

3. min vs default

   Two BYOB readers race over the same byte stream; the read-log columns visualise how many short reads min eliminates and where the partials land.

4. Protocol Decoder

   Length-prefixed binary protocol decoded with two reads per frame: 8 bytes for the header, then exactly len bytes for the body. No reassembly buffer.

5. Fixed-Frame Binary Reader

   Parses a simulated binary format (4-byte magic + 4-byte length + payload) from a stream that emits randomly-sized chunks. Two side-by-side readers: "without min" (shows partial reads and reassembly loops) vs "with min: 8" (zero reassembly). Read log shows timestamp, requested size, actual bytes returned, and whether each read yielded a complete frame.

why it shipped

The ReadableStreamBYOBReader.read(view) method allows developers to supply a buffer view into which stream data is read. However, the current behavior does not guarantee how many elements will be written into the buffer. The stream may resolve the read with fewer elements than the view can accommodate.

references

• ChromeStatus entry
• Spec