Function parameter explanation in Redux where a function returns a function?

Question

I do understand Redux a bit, but I don't understand how you can put a function inside a function.

import api from '../utils/api';

import {
  GET_PROFILE, PROFILE_ERROR
} from './types';

export const getCurrentProfile = () => async (dispatch) => {
  try {
    const res = await api.get('/profile/me');

    dispatch({
      type: GET_PROFILE,
      payload: res.data
    });
  } catch (err) {
    dispatch({
      type: PROFILE_ERROR,
      payload: { msg: err.response.statusText, status: err.response.status }
    });
  }
};

I am having issues with this line:

export const getCurrentProfile = () => **async (dispatch) => {}**

Are we defining our own function here with async (dispatch) => {}?
Why will we define our own function?
I know what dispatch does, but where do we get it and why are we using it on the two objects?
What is the name of this pattern, if any?

For the name, it's usually called a [curried function](https://stackoverflow.com/q/36314/1218980). — Emile Bergeron, Sep 12 '21 at 23:24
For the why of this pattern within Redux, it's mostly to [enable async redux action function, which is called redux thunks](https://stackoverflow.com/q/35411423/1218980). — Emile Bergeron, Sep 12 '21 at 23:27
@EmileBergeron thanks man you're awesome.!!! I need this in both Node.js and React — Ridwan Bin Monjur, Sep 13 '21 at 05:46

score 1 · Accepted Answer · answered Sep 12 '21 at 23:55

1

yes. The getCurrentProfile returns a new function that takes one parameter.
Maybe they will use the function in a closure. Closures can be used to hide information.
Whatever is using the function you create will give the dispatch to the function when it calls it.

answered Sep 12 '21 at 23:55

Alex

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Thanks so much @Alex. You're right of course and it solved my issue! – Ridwan Bin Monjur Sep 13 '21 at 05:46
@RidwanBinMonjur your welcome. mark my answer as correct please :) – Alex Sep 14 '21 at 04:27

Function parameter explanation in Redux where a function returns a function?

1 Answers1