reordering function

reorderList.ts

// function that will allow you to move an item within a list and will reposition the other items accordingly

type ListItem = {
  label: string;
  pos: number;
}

const list = [
  {
    label: "a",
    pos: 0
  },
  {
    label: "b",
    pos: 1
  },
  {
    label: "c",
    pos: 2
  },
  {
    label: "d",
    pos: 3
  },
  {
    label: "e",
    pos: 4
  },
  {
    label: "f",
    pos: 5
  },
  {
    label: "g",
    pos: 6
  },
  {
    label: "h",
    pos: 7
  }
];

function getIsBetweenRange(number: number, rangeStart: number, rangeEnd: number): boolean {
  return (
    number > Math.min(rangeStart, rangeEnd) &&
    number < Math.max(rangeStart, rangeEnd)
  );
}

function sortArrayOfObjectsByKey(array: ListItem[], sortKey: string, isAscending: boolean = true): ListItem[] {
  return [...array].sort((a, b): number => {
    const aValue = a[sortKey];
    const bValue = b[sortKey];
    if (aValue > bValue) return isAscending ? 1 : -1;
    if (aValue < bValue) return isAscending ? -1 : 1;
    return 0
  })
}

function moveTo(array: ListItem[], from: number, to: number): ListItem[] {
  // if item is not moving anywhere
  // no changes are necessary
  if (from === to) return array;
  return array.map(item => {
    const { label, pos } = item;
    // if current item is the one that is explicitly moving
    // set the new position
    if (pos === from) {
      return {
        label,
        pos: to
      };
    }
    // if current item is within the range of movement
    // or
    // is in the position where the item is moving to
    // shift it
    if (getIsBetweenRange(pos, from, to) || pos === to) {
      // if the moving item is moving up, shift other items down
      // if the moving item is moving down, shift other items up
      return { ...item, pos: from < to ? pos - 1 : pos + 1 };
    }
    // otherwise, the item is outside the range of movement
    // keep it in its current position
    return item;
  });
}

const newList = moveTo(list, 2, 6);
sortArrayOfObjectsByKey(newList, 'pos').forEach(item => {
  const { label, pos } = item;
  console.log(label, pos);
});