What's new in binary data?

Resizable buffers. A buffer created with maxByteLength can resize() in place up to that cap. A length-tracking view (new Uint8Array(buffer)) follows the buffer. A view with a fixed length or offset goes out of bounds when the buffer shrinks below it: length, byteLength, and byteOffset read 0 and methods throw TypeError. It recovers if the buffer grows back.

Transfer. buffer.transfer(newLength?) moves the bytes into a new buffer (truncated or zero-extended) and detaches the original: detached is true, byteLength is 0, and every view on it reports length 0. transfer keeps resizability, transferToFixedLength drops it. It is the language-level form of what postMessage(buf, [buf]) and structuredClone(buf, { transfer: [buf] }) already do.

Copying methods. Typed arrays gained toSorted, toReversed, and with, which return a new typed array instead of mutating.

Float16. Half-precision floats (1 sign, 5 exponent, 10 fraction bits) for compact numeric storage. Math.f16round(x) rounds a Number to the nearest representable half, and Float16Array stores them. Range tops out at 65504.

Base64 and hex. Built-in encoders replace the btoa(String.fromCharCode(...)) workaround, with alphabet: 'base64url', omitPadding, and a lastChunkHandling option for decoding.

// Node 22+ (resizable buffers, transfer)
const buffer = new ArrayBuffer(4, { maxByteLength: 16 });
const follows = new Uint8Array(buffer);       // length-tracking view
const pinned = new Uint8Array(buffer, 0, 4);  // fixed length 4

buffer.resize(8);
console.log(follows.length, pinned.length);
// → 8 4
buffer.resize(2);
console.log(follows.length, pinned.length); // pinned is now out of bounds
// → 2 0

follows[0] = 7;
const moved = buffer.transfer(4);             // detaches `buffer`, keeps it resizable
console.log(buffer.detached, buffer.byteLength, follows.length);
// → true 0 0
console.log(moved.byteLength, moved.resizable, new Uint8Array(moved)[0]);
// → 4 true 7

• Shipping base64 or hex methods unguarded. They are missing in Node 22 and 24, and in browsers older than Chrome 140, Firefox 133, or Safari 18.2 (per MDN). Check typeof Uint8Array.fromBase64 === 'function' and keep a btoa or Buffer fallback.
• Using a detached buffer. After transfer() or a transferable postMessage, slice and new Uint8Array(oldBuffer) throw TypeError, and old views silently read 0 length. Check buffer.detached when ownership is unclear.
• Caching view.length across a resize. A length-tracking view changes length when the buffer is resized, and a fixed view can go out of bounds. Re-read length, don't store it.
• Expecting Float16Array precision. Half floats hold about 3 decimal digits: Math.f16round(0.1) is 0.0999755859375, and values above 65504 round to Infinity.