Function pop

dash/deps/react@16.14.0.js:2252–2267

(heap)

    return first === undefined ? null : first;
  }
  function pop(heap) {
    var first = heap[0];

    if (first !== undefined) {
      var last = heap.pop();

      if (last !== first) {
        heap[0] = last;
        siftDown(heap, last, 0);
      }

      return first;
    } else {
      return null;
    }
  }

  function siftUp(heap, node, i) {
    var index = i;