Tiny Typescript implementation of CRC32

Crc32.ts

const POLYNOMIAL = -306674912;

let crc32_table: Int32Array = undefined;

export function Crc32(bytes: Uint8Array, crc=0xFFFFFFFF) {
  if (crc32_table === undefined)
    calcTable();
  for (let i = 0; i < bytes.length; ++i)
    crc = crc32_table[(crc ^ bytes[i]) & 0xff] ^ (crc >>> 8);
  return (crc ^ -1) >>> 0;
}

function calcTable() {
  crc32_table = new Int32Array(256);
  for(let i = 0; i < 256; i++) {
    let r = i;
    for (let bit = 8; bit > 0; --bit)
      r = ((r & 1) ? ((r >>> 1) ^ POLYNOMIAL) : (r >>> 1));
    crc32_table[i] = r;
  }  
}