Function updateVNode

src/List.js:507–549

(node, ownerID, level, index, value, didAlter)

}

function updateVNode(node, ownerID, level, index, value, didAlter) {
  const idx = (index >>> level) & MASK;
  const nodeHas = node && idx < node.array.length;
  if (!nodeHas && value === undefined) {
    return node;
  }

  let newNode;

  if (level > 0) {
    const lowerNode = node && node.array[idx];
    const newLowerNode = updateVNode(
      lowerNode,
      ownerID,
      level - SHIFT,
      index,
      value,
      didAlter
    );
    if (newLowerNode === lowerNode) {
      return node;
    }
    newNode = editableVNode(node, ownerID);
    newNode.array[idx] = newLowerNode;
    return newNode;
  }

  if (nodeHas && node.array[idx] === value) {
    return node;
  }

  if (didAlter) {
    SetRef(didAlter);
  }

  newNode = editableVNode(node, ownerID);
  if (value === undefined && idx === newNode.array.length - 1) {
    newNode.array.pop();
  } else {
    newNode.array[idx] = value;
  }
  return newNode;
}

function editableVNode(node, ownerID) {
  if (ownerID && node && ownerID === node.ownerID) {