gistfile1.js

function crc32(s/*, polynomial = 0x04C11DB7, initialValue = 0xFFFFFFFF, finalXORValue = 0xFFFFFFFF*/) {
  s = String(s);
  var polynomial = arguments.length < 2 ? 0x04C11DB7 : arguments[1],
      initialValue = arguments.length < 3 ? 0xFFFFFFFF : arguments[2],
      finalXORValue = arguments.length < 4 ? 0xFFFFFFFF : arguments[3],
      crc = initialValue,
      table = [], i, j, c;

  function reverse(x, n) {
    var b = 0;
    while (n) {
      b = b * 2 + x % 2;
      x /= 2;
      x -= x % 1;
      n--;
    }
    return b;
  }

  for (i = 255; i >= 0; i--) {
    c = reverse(i, 32);

    for (j = 0; j < 8; j++) {
      c = ((c * 2) ^ (((c >>> 31) % 2) * polynomial)) >>> 0;
    }

    table[i] = reverse(c, 32);
  }

  for (i = 0; i < s.length; i++) {
    c = s.charCodeAt(i);
    if (c > 255) {
      throw new RangeError();
    }
    j = (crc % 256) ^ c;
    crc = ((crc / 256) ^ table[j]) >>> 0;
  }

  return (crc ^ finalXORValue) >>> 0;
}

alert(crc32('test').toString(16));//D87F7E0C
alert(crc32('test', 0x04c11db7, 0, 0xFFFFFFFF).toString(16));//6C45EEF
alert(crc32('test', 0x04c11db7, 0xFFFFFFFF, 0).toString(16));//278081F3
alert(crc32('test', 0x04c11db7, 0, 0).toString(16));//F93BA110