Let's assume that our API's URL is "https://jsonplaceholder.typicode.com/posts" . First we have to add this URL in src/helpers/url_helper.ts file

  export const GET_DEMO_DATA = "https://jsonplaceholder.typicode.com/posts"; 

Whatever methods you want to use, import it import { APIClient } from "src/helpers/api_helper"; and add below function in src/helpers/fakebackend_helper.ts file. We have created new function getDemoData and exported it so it can be used in another files.

  import { APIClient } from "./api_helper";
  import * as url from "./url_helper"
  
  const getDemoData = () => api.get(url.GET_DEMO_DATA);
                
  export { getDemoData };

create reducer.ts file, Reducers are used in APIs to manage the state of the API. They are typically used in conjunction with the getState and dispatch methods, which allow you to get the current state of the API and dispatch an action to the API, respectively.

  import { createSlice } from "@reduxjs/toolkit"; 
  export const initialState = {
      forgetSuccessMsg: null,
      forgetError: null,
    };    
  
  const demoSlice = createSlice({
    name:"",
    initialState,
    reducers:{
      demoSuccess(state, action) {
        state.forgetSuccessMsg = action.payload
      },
      demoError(state, action) {
        state.forgetError = action.payload
      },
    },
  });
  
  export const {
    demoSuccess,
    demoError
  } = demoSlice.actions
  
  export default demoSlice.reducer;

Create thunk.ts file , Thunk is used for APIs because it allows you to perform asynchronous operations, such as making HTTP requests, within the context of a Redux action. This is useful because it allows you to keep your Redux state consistent and predictable, even when you are making asynchronous requests .

  import { demoSuccess, demoError } from "./reducer"  
  
  const demoData = () => async(dispatch) => {
    try {
      let response;

      const data = await response;

      if (data) {
        dispatch(demoSuccess(
          "message"
        ))
      } catch (forgetError) {
        dispatch(demoError(forgetError))
      }
    }

  }
  export default demoData;