Function mapChildren

packages/react/src/ReactChildren.js:357–372

* Maps children that are typically specified as `props.children`. * * See https://reactjs.org/docs/react-api.html#reactchildrenmap * * The provided mapFunction(child, index) will be called for each * leaf child. * * @param {?*} children Children tree container. * @param {function(*, int)} fu

(
  children: ?ReactNodeList,
  func: MapFunc,
  context: mixed,
)

 * @return {object} Object containing the ordered map of results.
 */
function mapChildren(
  children: ?ReactNodeList,
  func: MapFunc,
  context: mixed,
): ?Array<React$Node> {
  if (children == null) {
    // $FlowFixMe limitation refining abstract types in Flow
    return children;
  }
  const result: Array<React$Node> = [];
  let count = 0;
  mapIntoArray(children, result, '', '', function (child) {
    return func.call(context, child, count++);
  });
  return result;
}

/**
 * Count the number of children that are typically specified as