javascript ->> 在 JavaScript 中做什么？

Question

在审查“Crossfilter”源代码时，我遇到了一个使用 >> 的函数。下面是函数:

  // Similar to bisectLeft, but returns an insertion point which comes after (to
  // the right of) any existing entries of x in a.
  //
  // The returned insertion point i partitions the array into two halves so that
  // all v <= x for v in a[lo:i] for the left side and all v > x for v in
  // a[i:hi] for the right side.

  function bisectRight(a, x, lo, hi) {
    while (lo < hi) {
      var mid = lo + hi >> 1;
      if (x < f(a[mid])) hi = mid;
      else lo = mid + 1;
    }
    return lo;
  }

Google 没有返回任何结果，我以前从未见过这种情况。预先感谢您的帮助。

Answer 1

这是 sign-propagating right shift operator :

This operator shifts the first operand the specified number of bits to the right. Excess bits shifted off to the right are discarded. Copies of the leftmost bit are shifted in from the left. Since the new leftmost bit has the same value as the previous leftmost bit, the sign bit (the leftmost bit) does not change. Hence the name "sign-propagating".