@portabletext/editor/src/internal-utils/move-range-by-operation.ts

Portable Text Editor made in React

import {Point, type Operation, type Range} from 'slate'

export function moveRangeByOperation(
  range: Range,
  operation: Operation,
): Range | null {
  const anchor = Point.transform(range.anchor, operation)
  const focus = Point.transform(range.focus, operation)

  if (anchor === null || focus === null) {
    return null
  }

  if (Point.equals(anchor, range.anchor) && Point.equals(focus, range.focus)) {
    return range
  }

  return {anchor, focus}
}