strange javascript operators from npm repeat-string >>= and &

javascript_operators.js

//while (max > res.length && num > 0) {
    if (num & 1) { // 1 if num is odd
    //  res += str;
    }

    num >>= 1; // halfs num to an integer (rounded down)
    // if (!num) break;
    // str += str;
  //{