text: 
  const crcTable = [
  	0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f,
  	0xe963a535, 0x9e6495a3,	0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
  	0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2,
  	0xf3b97148, 0x84be41de,	0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
  	0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec,	0x14015c4f, 0x63066cd9,
  	0xfa0f3d63, 0x8d080df5,	0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
  	0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,	0x35b5a8fa, 0x42b2986c,
  	0xdbbbc9d6, 0xacbcf940,	0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
  	0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423,
  	0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
  	0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d,	0x76dc4190, 0x01db7106,
  	0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
  	0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d,
  	0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
  	0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
  	0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
  	0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7,
  	0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
  	0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa,
  	0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
  	0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81,
  	0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
  	0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84,
  	0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
  	0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
  	0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
  	0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e,
  	0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
  	0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55,
  	0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
  	0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28,
  	0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
  	0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f,
  	0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
  	0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
  	0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
  	0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69,
  	0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
  	0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc,
  	0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
  	0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693,
  	0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
  	0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
  ];
  
  
  /**
   * Calculates a 4-byte CRC32 of a string or byte array
   */
  export class Crc32 {
  
      /**
       * Convert a string to an array of UTF-8 bytes
       * @param {string} str string to convert
       * @return {array} of bytes
       */
      static stringToBytes(str) {
          let bytes = [];
          for (let i = 0, len = str.length; i < len; i++) {
              let code = str.charCodeAt(i);
              if (code < 0x80) {
                  bytes.push(code);
              } else if (code < 0x800) {
                  bytes.push(0xc0 | (code >> 6),
                      0x80 | (code & 0x3f));
              } else if (code < 0xd800 || code >= 0xe000) {
                  bytes.push(0xe0 | (code >> 12),
                      0x80 | ((code >> 6) & 0x3f),
                      0x80 | (code & 0x3f));
              } else { // surrogate pair
                  i++;
                  /**
                   * UTF-16 encodes 0x10000-0x10FFFF by
                   * subtracting 0x10000 and splitting the
                   * 20 bits of 0x0-0xFFFFF into two halves
                   */
                  code = 0x10000 + (((code & 0x3ff) << 10) |
                      (str.codeAt(i) & 0x3ff));
                  bytes.push(0xf0 | (code >> 18),
                      0x80 | ((code >> 12) & 0x3f),
                      0x80 | ((code >> 6) & 0x3f),
                      0x80 | (code & 0x3f));
              }
          }
          return bytes;
      }
  
      /**
       * Calculate the crc32 checksum for a string
       * @param {string} str input string
       * @return {number} the crc
       */
      static ofString(str) {
          let bytes = this.stringToBytes(str);
          return this.ofBytes(bytes);
      }
  
      /**
       * Calculate the crc32 checksum for an array of bytes
       * @param {array} bytes array of bytes
       * @return {number} the crc
       */
      static ofBytes(bytes) {
          let crc = 0 ^ (-1);
          for (let byte of bytes) {
              crc = (crc >>> 8) ^ crcTable[(crc ^ byte) & 0xff];
          }
          return (crc ^ (-1)) >>> 0;
      }
  
      /**
       * break a 32-bit crc into 4 bytes, so that they can be sent as payload.
       * @param {number} the crc to break apart
       * @return {array} the 4 bytes
       */
      static intToBytes(crc) {
          let bytes = [
              (crc >> 24) & 0xff,
              (crc >> 16) & 0xff,
              (crc >> 8) & 0xff,
              (crc) & 0xff
          ];
          return bytes;
      }
  
      /**
       * reconstitute the int from intoToBytes
       * @param {array} bytes the 4 bytes to decode
       * @return {number} the original int
       */
      static bytesToInt(bytes) {
  		let v = bytes[0];
  		v = v << 8 | bytes[1];
  		v = v << 8 | bytes[2];
  		v = v << 8 | bytes[3];
  		return v >>> 0;
      }
  
      /**
       * break a 32-bit crc into 4 bytes, so that they can be sent as payload.
       * @param {number} the crc to break apart
       * @return {array} the 4 bytes
       */
      static intToBytesLE(crc) {
          let bytes = [
              (crc) & 0xff,
              (crc >> 8) & 0xff,
              (crc >> 16) & 0xff,
              (crc >> 24) & 0xff
          ];
          return bytes;
      }
  
  }
  
  Crc32.table = crcTable;
  
  