Don't forget about proposal-arraybuffer-base64

[gibson042]

Uint8Array.prototype.setFromBase64 and Uint8Array.prototype.setFromHex will need to reject receivers backed by immutable buffers, probably by extending ValidateUint8Array with an optional accessMode parameter to match the extension of ValidateTypedArray.

[conartist6]

Would there be a secret internal bit marking the buffer as frozen? If not the validator could be easily hoodwinked: #61 If so, some method to access that secret internal bit would be very nice to have so that it is possible to reflectively tell whether it is safe to call APIs which have specific needs regarding immutable data (without wrapping them in try/catch)

[conartist6]

Ok so the answer is yes: there is a secret internal bit, and it can be accessed with ArrayBuffer.prototype.immutable.call

[ljharb]

Object.getOwnPropertyDescriptor(ArrayBuffer.prototype, 'immutable').get, yes.