@blocknote/core/src/api/positionMapping.ts

A "Notion-style" block-based extensible text editor built on top of Prosemirror and Tiptap.

import type { BlockNoteEditor } from "../editor/BlockNoteEditor.js";
import type { PositionMappingExtension } from "../extensions/PositionMapping/PositionMapping.js";

/**
 * This is used to keep track of positions of elements in the editor.
 * It is needed because y-prosemirror's sync plugin can disrupt normal prosemirror position mapping.
 *
 * It is specifically made to be able to be used whether the editor is being used in a collaboratively, or single user, providing the same API.
 *
 * @param editor The editor to track the position of.
 * @param position The position to track.
 * @param side The side of the position to track. "left" is the default. "right" would move with the change if the change is in the right direction.
 * @returns A function that returns the position of the element.
 */
export function trackPosition(
  /**
   * The editor to track the position of.
   */
  editor: BlockNoteEditor<any, any, any>,
  /**
   * The position to track.
   */
  position: number,
  /**
   * This is the side of the position to track. "left" is the default. "right" would move with the change if the change is in the right direction.
   */
  side: "left" | "right" = "left",
): () => number {
  // Try to use the Yjs Relative Position Mapping Extension
  const yPositionMappingExtension =
    editor.getExtension<typeof PositionMappingExtension>("yPositionMapping");
  if (yPositionMappingExtension) {
    return yPositionMappingExtension.mapPosition(position, side);
  }
  // Fallback to the Prosemirror Position Mapping Extension
  const positionMappingExtension =
    editor.getExtension<typeof PositionMappingExtension>("positionMapping");
  if (positionMappingExtension) {
    return positionMappingExtension.mapPosition(position, side);
  }
  throw new Error("No position mapping extension found");
}