What does operator >>= mean

Question

What exactly does the >>= operator mean in JavaScript? I mean, I use it often in Haskell to work with monadic values, but I saw this weird (and syntactically valid!) operator in a JavaScript code:

function repeatArray$(arr, n){
  for (var r = []; n > 0; (n >>= 1) && (arr = arr.concat(arr)))
    if (n & 1) r.push.apply(r, arr);
  return r;
}

I know what the function does, but I can't resolve the utility here or what it can do. Is it a composition of two operators, such as --> (-- >) with bitwise operations? I didn't find a specification about that.

Answer 1

x >>= y is Right Shift assignment. Equivalent to x = x >> y.

MDN Assignment Operators