Function insertInJSXTextAtOffset

packages/cli/src/transform.ts:1501–1562

* Insert text at a character offset within the concatenated JSXText of a subtree. * Walks through JSXText nodes, tracking cumulative offset, and inserts when found.

(node: any, offset: number, insertion: string, source?: string)

 * Walks through JSXText nodes, tracking cumulative offset, and inserts when found.
 */
function insertInJSXTextAtOffset(node: any, offset: number, insertion: string, source?: string): boolean {
  const segments = buildImmediateTextSegments(node, source);
  if (segments.length === 0) return false;

  let cursor = 0;
  for (let i = 0; i < segments.length; i++) {
    const segment = segments[i];
    const segmentStart = cursor;
    const segmentEnd = cursor + segment.text.length;
    cursor = segmentEnd;

    if (offset < segmentStart || offset > segmentEnd) continue;

    if (segment.type === "boundary") {
      return insertBetweenImmediateChildren(node, segment.leftChildIndex, segment.rightChildIndex, insertion, segment.text);
    }

    const child = node.children?.[segment.childIndex];
    if (!child) return false;

    const nextSegment = segments[i + 1];
    if (
      offset === segmentEnd &&
      nextSegment?.type === "child" &&
      nextSegment.childIndex !== segment.childIndex
    ) {
      return insertBetweenImmediateChildren(node, segment.childIndex, nextSegment.childIndex, insertion);
    }

    if (child.type === "JSXText") {
      const rawOffset = mapRenderedOffsetToRawIndex(child.value, Math.max(0, offset - segmentStart), "end");
      const localOffset = Math.max(0, Math.min(child.value.length, rawOffset));
      child.value = child.value.slice(0, localOffset) + insertion + child.value.slice(localOffset);
      return true;
    }

    if (child.type === "JSXElement") {
      return insertInJSXTextAtOffset(child, offset - segmentStart, insertion, source);
    }

    if (child.type === "JSXExpressionContainer" && child.expression?.type === "StringLiteral") {
      const value = String(child.expression.value ?? "");
      const rawOffset = mapRenderedOffsetToRawIndex(value, Math.max(0, offset - segmentStart), "end");
      const localOffset = Math.max(0, Math.min(value.length, rawOffset));
      child.expression.value = value.slice(0, localOffset) + insertion + value.slice(localOffset);
      return true;
    }

    return false;
  }

  const lastSegment = segments[segments.length - 1];
  if (lastSegment.type === "child") {
    const child = node.children?.[lastSegment.childIndex];
    if (child?.type === "JSXText") {
      child.value += insertion;
      return true;
    }