redux - prevent too many request

Commit

https://github.com/shooeugenesea/study-js/commit/ad54df277bb17c12cf9f3bb37f965b13945ae68b

By current implementation, many requests are sent

In order to prevent too many redundant requests, use lodash memoize to reduce.

npm install -save lodash

Then change src/actions/index.js

import _ from 'lodash'

// assign fetchUser to memoize, so that function instance is the same

export const fetchUser = (userId) => dispatch => _fetchUser(userId, dispatch);

// define a function to adapt memoize

const _fetchUser = _.memoize(async (userId, dispatch) => {

    const response = await jsonPlaceholder.get(`/users/${userId}`)

    dispatch({type:'FETCH_USER', payload: response.data})

})

request and response are cached, so no redundant request will be sent