I'm sure you will find this helpful: http://jsdo.it/tsmallfield/uint8array.

Click on javascript tab. There will appear the code to convert the Uint8Array in a string. The author shows 2 method:

• The first is about creating a view.
• The second offsetting bytes.

EDIT: report the code for completeness

var buffer = new ArrayBuffer( res.length ), // res is this.response in your case
    view   = new Uint8Array( buffer ),
    len    = view.length,
    fromCharCode = String.fromCharCode,
    i, s, str;    

/**
 *  1) 8bitの配列に入れて上位ビットけずる
 */
str = "";

for ( i = len; i--; ) {
  view[i] = res[i].charCodeAt(0);
}

for ( i = 0; i < len; ++i ) {
  str += fromCharCode( view[i] );
}    

/**
 *  2) & 0xff で上位ビットけずる
 */
str = "";

for ( i = 0; i < len; ++i ) {
  str += fromCharCode( res[i].charCodeAt(0) & 0xff );
}

Update 2018 - The easiest way in 2018 should be TextEncoder

let utf8Encode = new TextEncoder();
utf8Encode.encode("abc");
// Uint8Array [ 97, 98, 99 ]

Caveats - The returned element is a Uint8Array, and not all browsers support it.

You need to parse each octet back to number, and use that value to get a character, something like this:

function bin2String(array) {
  var result = "";
  for (var i = 0; i < array.length; i++) {
    result += String.fromCharCode(parseInt(array[i], 2));
  }
  return result;
}

bin2String(["01100110", "01101111", "01101111"]); // "foo"

// Using your string2Bin function to test:
bin2String(string2Bin("hello world")) === "hello world";

Edit: Yes, your current string2Bin can be written more shortly:

function string2Bin(str) {
  var result = [];
  for (var i = 0; i < str.length; i++) {
    result.push(str.charCodeAt(i).toString(2));
  }
  return result;
}

But by looking at the documentation you linked, I think that the setBytesParameter method expects that the blob array contains the decimal numbers, not a bit string, so you could write something like this:

function string2Bin(str) {
  var result = [];
  for (var i = 0; i < str.length; i++) {
    result.push(str.charCodeAt(i));
  }
  return result;
}

function bin2String(array) {
  return String.fromCharCode.apply(String, array);
}

string2Bin('foo'); // [102, 111, 111]
bin2String(string2Bin('foo')) === 'foo'; // true

Java is interpreting the byte as being a signed two's-complement number, which is negative since the highest bit is 1. Javascript is interpreting it as unsigned, so it's always positive.

Try this:

var b1 = parseInt('11100011', 2);
if(b1 > 127) b1 -= 256;

Update: I'm not so sure [default] Ajax is the right tool for the job in this case. Regardless of file size, it is generally a good practice to use streams instead to accommodate future scalability, as your current method loads everything at once.

This article goes over how to create a custom ajax transport that wraps an XmlHttpRequest to load the data into an array buffer rather. You could do this, sequentially push the bytes into your main array, and go from there.

Old: I'm not sure if I properly understood your data representation, but I believe you can just use parseInt() to turn a hex string into decimal:

var data = ['0x00', '0x08', '0x17', '0xA1', '0x01'];
var parsed = [];

for(var i = 0; i < data.length; i++) {
	parsed.push(parseInt(data[i], 16));
}

console.log(parsed);
console.log(parseInt('0xA1', 16))

If this is not what you mean, please comment and I will try to update my answer with a more specific implementation.

Your data string seems to contain only extended ASCII characters (probably either Windows-1252 characters or ISO 8859-1 characters). You should try using a System.Text.Encoding to convert it to bytes.

It seems I missed the example within the Chrome documentation.

var message = new Uint8Array(3);
message[0] = 1;
message[1] = 2;
message[3] = 3;

var binaryMessage = message.buffer;

Parse it to an integer in base 2, then convert to a byte array. In fact, since you've got 16 bits it's time to break out the rarely used short.

short a = Short.parseShort(b, 2);
ByteBuffer bytes = ByteBuffer.allocate(2).putShort(a);

byte[] array = bytes.array();