Function getPosition

packages/react-aria/src/tokenfield/useTokenField.ts:622–664

(container: Element, node: Node, offset: number)

}

function getPosition(container: Element, node: Node, offset: number): Position {
  if (node === container) {
    return {index: offset, offset: 0};
  }

  let originalNode = node;
  while (node.parentNode !== container) {
    node = node.parentNode!;
  }

  let index = indexOfNode(node);
  if (node.nodeType === Node.ELEMENT_NODE) {
    let tokenNode = node.childNodes[1];
    let atEnd: boolean;
    let endOffset = 0;
    if (originalNode === tokenNode) {
      // Cursor is inside the token.
      atEnd = offset > 0;
    } else if (originalNode === node) {
      // Cursor is inside the wrapper element.
      atEnd = offset > 1;
    } else {
      // Cursor is on one of the zero width spaces.
      atEnd = originalNode !== tokenNode.previousSibling;
      // If the offset is greater than 1, the browser is trying to insert text into
      // the zero width space node. This will actually end up in the next text node.
      endOffset = atEnd && offset > 1 ? offset - 1 : 0;
    }

    offset = atEnd ? (tokenNode?.textContent?.length ?? 0) : 0;

    // Several positions are equivalent due to the zero width spaces around tokens.
    // Normalize offset to the end of the preceding text node, or the beginning of the following node.
    if (offset === 0 && node.previousSibling?.nodeType === Node.TEXT_NODE) {
      index--;
      offset = node.previousSibling?.textContent?.length ?? 0;
    } else if (atEnd) {
      index++;
      offset = endOffset;
    }
  }
  return {index, offset};
}

let isProgrammaticSelectionChange = Symbol('isProgrammaticSelectionChange');