How to use the prosemirror-transform.joinPoint function in prosemirror-transform

export default function joinUp(tr: Transform): Transform {
  const sel = tr.selection;
  const nodeSel = sel instanceof NodeSelection;
  let point;
  if (nodeSel) {
    if (sel.node.isTextblock || !canJoin(tr.doc, sel.from)) {
      return tr;
    }
    point = sel.from;
  } else {
    point = joinPoint(tr.doc, sel.from, -1);
    if (point === null || point === undefined) {
      return tr;
    }
  }

  tr = tr.join(point);
  if (nodeSel) {
    tr = tr.setSelection(
      NodeSelection.create(
        tr.doc,
        point - tr.doc.resolve(point).nodeBefore.nodeSize
      )
    );
  }

  return tr;

export function joinUp(state, dispatch) {
  let sel = state.selection, nodeSel = sel instanceof NodeSelection, point
  if (nodeSel) {
    if (sel.node.isTextblock || !canJoin(state.doc, sel.from)) return false
    point = sel.from
  } else {
    point = joinPoint(state.doc, sel.from, -1)
    if (point == null) return false
  }
  if (dispatch) {
    let tr = state.tr.join(point)
    if (nodeSel) tr.setSelection(NodeSelection.create(tr.doc, point - state.doc.resolve(point).nodeBefore.nodeSize))
    dispatch(tr.scrollIntoView())
  }
  return true
}

export function joinDown(state, dispatch) {
  let sel = state.selection, point
  if (sel instanceof NodeSelection) {
    if (sel.node.isTextblock || !canJoin(state.doc, sel.to)) return false
    point = sel.to
  } else {
    point = joinPoint(state.doc, sel.to, 1)
    if (point == null) return false
  }
  if (dispatch)
    dispatch(state.tr.join(point).scrollIntoView())
  return true
}

export default function joinDown(tr: Transform): Transform {
  const sel = tr.selection;
  let point;
  if (sel instanceof NodeSelection) {
    if (sel.node.isTextblock || !canJoin(tr.doc, sel.to)) {
      return tr;
    }
    point = sel.to;
  } else {
    point = joinPoint(tr.doc, sel.to, 1);
    if (point === null || point === undefined) {
      return tr;
    }
  }
  tr = tr.join(point);
  return tr;
}