unitSelectorSlice.js

import { createSlice } from '@reduxjs/toolkit';

const unitSelectorSlice = createSlice({
  name: 'unitSelector',
  initialState: {
    currentInputUnit: 'in',
    currentOutputUnit: 'in',
  },
  reducers: {
    // The action payload should have the unit to switch to with the in or out
    setCurrentInputUnit: (state, action) => {
      const newUnit = action.payload;
      return {
        ...state,
        currentInputUnit: newUnit,
      };
    },
    setCurrentOutputUnit: (state, action) => {
      const newUnit = action.payload;
      return {
        ...state,
        currentOutputUnit: newUnit,
      };
    },
  },
});
export default unitSelectorSlice;

export const {
  setCurrentInputUnit,
  setCurrentOutputUnit,
} = unitSelectorSlice.actions;

export function selectCurrentInputUnit(state) {
  return state.unitSelector.currentInputUnit;
}