// This is what I'm trying to implement:
//
// A function which takes raw data (ArrayBuffer) and
// returns the data as a raw "binary" string,
// just as you would get if you used FileReader.readAsBinaryString().
function BytesToString(bytes) {
  return String.fromCharCode.apply(null, new Uint8Array(bytes));
}

// Working with a small buffer works fine:
const smallData = new Uint8Array([
  72,  // 'H'
  101, // 'e'
  108, // 'l'
  108, // 'l'
  111, // 'o'
  33,  // '!'
  0,   // raw byte 0x00
  238, // raw byte 0xEE
]);
console.log(smallData);
console.log(BytesToString(smallData));

// The problem is it falls apart for larger buffers,
// even if the size is still "reasonable" (2**20 == one megabyte)
//
// In Chrome this results in the somewhat-misleading error,
// "Unhandled Rejection (RangeError): Maximum call stack size exceeded".
//
// This is disabled in order to show the rest of the example without a crash.
// Change "false" to "true" to enable it:
const showIssue = false;
if (showIssue) {
  var bigData = new ArrayBuffer(2**20);
  var bigDataBytes = new Uint8Array(bigData);
  for (var i = 0; i < bigData.byteLength; ++i) {
    bigDataBytes[i] = 88; // 'X'
  }
  console.log(bigDataBytes);
  console.log(BytesToString(bigData));
}

// As an alternative I tried to use TextEncoder/TextDecoder, but
// the encoder thinks the data should be written as a list of numbers
// and not as a raw string.  (I don't really like this method anyway
// because it introduces a needless encoding to UTF-8 and then
// decoding back to the original code points.)
var encoder = new TextEncoder();
var decoder = new TextDecoder();
const encoding = encoder.encode(smallData);
const decoding = decoder.decode(encoding);
console.log(encoding);
console.log(decoding);

// I can't simply use TextDecoder alone, because it mis-interprets
// the input as being UTF-8 encoded.  Because the raw byte 0xEE is not
// a valid UTF-8 sequence, the last character is replaced by the "Unicode
// replacement character (�)":
console.log(decoder.decode(smallData));