w7d2 - Redux/middleware

Question 1

How do you assign a namespace to a rails resource? What does this change? What is a namespace?

Answer 1

A namespace is a subset of controllers that live under a specific URL.

namespace :api do
resources :cats
end

This will change the url-helper method from cats into api_cats.

This will change the url for cats from /cats to /api/cats

Question 2

How do we ensure that our state is immutable?

Answer 2

Call Object.freeze(state) at the top of every reducer. This will ensure that the state is never accidentally mutated.

Question 3

What is the limitation of Object.freeze ?

Answer 3

It is not a deep-freeze. Sub-elements within the frozen object can still be mutated.

Question 4

Does an ES6 fat-arrow function create a new scope?

Answer 4

No. It is not lexically scoped. ‘this’ means the same thing inside an arrow function that it does outside of it.

Question 5

How is middleware installed into a store?

How would you set up a logger?

Answer 5

It’s passed along when a store is created:

createStore( reducer, preLoadedState, enhancer )

An example of the ‘enhancer’ param:

///////////

import { createStore, applyMiddleware } from ‘redux’;
import { logger } from ‘redux-logger’;

createStore( reducer, preLoadedState, applyMiddleware(logger) )

Question 6

When writing your own middleware, what signature must be followed?

Answer 6

const myMiddleware = store => next => action => {
 // my side effects
 return next(action);
};

Question 7

What npm package allows us to log changes to our store’s state?

Answer 7

redux-logger

Question 8

What’s the purpose of using a Thunk?

Answer 8

To handle asynchronous calls via action creators. By doing so, we keep all async calls in one location, rather than having them randomly strewn throughout our components.