Function mapIntoArray

packages/react/src/ReactChildren.js:146–340

(
  children: ?ReactNodeList,
  array: Array<React$Node>,
  escapedPrefix: string,
  nameSoFar: string,
  callback: (?React$Node) => ?ReactNodeList,
)

}

function mapIntoArray(
  children: ?ReactNodeList,
  array: Array<React$Node>,
  escapedPrefix: string,
  nameSoFar: string,
  callback: (?React$Node) => ?ReactNodeList,
): number {
  const type = typeof children;

  if (type === class="st">'undefined' || type === class="st">'boolean') {
    class="cm">// All of the above are perceived as null.
    children = null;
  }

  let invokeCallback = false;

  if (children === null) {
    invokeCallback = true;
  } else {
    switch (type) {
      case class="st">'bigint':
      case class="st">'string':
      case class="st">'number':
        invokeCallback = true;
        break;
      case class="st">'object':
        switch ((children: any).$$typeof) {
          case REACT_ELEMENT_TYPE:
          case REACT_PORTAL_TYPE:
            invokeCallback = true;
            break;
          case REACT_LAZY_TYPE:
            const payload = (children: any)._payload;
            const init = (children: any)._init;
            return mapIntoArray(
              init(payload),
              array,
              escapedPrefix,
              nameSoFar,
              callback,
            );
        }
    }
  }

  if (invokeCallback) {
    const child = children;
    let mappedChild = callback(child);
    class="cm">// If it's the only child, treat the name as if it was wrapped in an array
    class="cm">// so that it's consistent if the number of children grows:
    const childKey =
      nameSoFar === class="st">'' ? SEPARATOR + getElementKey(child, 0) : nameSoFar;
    if (isArray(mappedChild)) {
      let escapedChildKey = class="st">'';
      if (childKey != null) {
        escapedChildKey = escapeUserProvidedKey(childKey) + class="st">'/';
      }
      mapIntoArray(mappedChild, array, escapedChildKey, class="st">'', c => c);