create-react-app with a server example

This project demonstrates using the setup generated by create-react-app alongside a Node Express API server.

Original blog post that explains the fundamentals of this repository.

Observations

Have trouble when using this repo with version 12 of Node. Back to 9.5. See .nvmrc file.

Run first:

nvm use

CORS

Véase branch: 10-crguezl-master-cors-01

Si en Client-jscambiamos el fetch para solicitar al server en 3001:

* eslint-disable no-undef */
function search(query, cb) {
  return fetch(`http://localhost:3001/api/food?q=${query}`, {
    accept: "application/json"
  })
    .then(checkStatus)
    .then(parseJSON)
    .then(cb);
}

Obtenemos una respuesta:

Access to fetch at 'http://localhost:3001/api/food?q=r' from origin 'http://localhost:3000' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.

localhost/:1 Uncaught (in promise) TypeError: Failed to fetch

If you want to avoid the blocking, the server that hosts the resource needs to have CORS enabled. What you can do on the client side (and probably what you are thinking of) is set the mode of fetch to CORS (although this is the default setting I believe):

fetch(request, {mode: 'cors'});

However this still requires the server to enable CORS as well, and allow your domain to request the resource.

In Express we can use the module cors

$ npm install cors

If inside the app we use this middleware:

var express = require('express')
var cors = require('cors')
var app = express()

app.use(cors())

app.get('/products/:id', function (req, res, next) {
  res.json({msg: 'This is CORS-enabled for all origins!'})
})

app.listen(80, function () {
  console.log('CORS-enabled web server listening on port 80')
})

To enable CORS for a Single Route we do:

var express = require('express')
var cors = require('cors')
var app = express()

app.get('/products/:id', cors(), function (req, res, next) {
  res.json({msg: 'This is CORS-enabled for a Single Route'})
})

app.listen(80, function () {
  console.log('CORS-enabled web server listening on port 80')
})

We can configure CORS:

var express = require('express')
var cors = require('cors')
var app = express()

var corsOptions = {
  origin: 'http://example.com',
  optionsSuccessStatus: 200 // some legacy browsers (IE11, various SmartTVs) choke on 204
}

app.get('/products/:id', cors(corsOptions), function (req, res, next) {
  res.json({msg: 'This is CORS-enabled for only example.com.'})
})

app.listen(80, function () {
  console.log('CORS-enabled web server listening on port 80')
})

The origin option used in this example configures the Access-Control-Allow-Origin CORS header. Possible values:

• Boolean - set origin to true to reflect the request origin, as defined by req.header('Origin'), or set it to false to disable CORS.
• String - set origin to a specific origin. For example if you set it to "http://example.com" only requests from “http://example.com” will be allowed.
• RegExp - set origin to a regular expression pattern which will be used to test the request origin. If it’s a match, the request origin will be reflected. For example the pattern /example\.com$/ will reflect any request that is coming from an origin ending with “example.com”.
• Array - set origin to an array of valid origins. Each origin can be a String or a RegExp. For example ["http://example1.com", /\.example2\.com$/] will accept any request from “http://example1.com” or from a subdomain of “example2.com”.
• Function - set origin to a function implementing some custom logic. The function takes the request origin as the first parameter and a callback (which expects the signature err [object], allow [bool]) as the second.

CORS references

• Using CORS in Express by Alexis Hevia
  • Repo with examples of use
• fetch
  • Referrer Policies
  • W3C
• cors is a node.js package for providing a Connect/Express middleware that can be used to enable CORS with various options.

Detailed blog post

We have a detailed blog post that explains this repository.

Rails

Check out the Rails version if that's your preferred API server platform.

Running locally

git clone https://github.com/fullstackreact/food-lookup-demo.git
cd food-lookup-demo
npm i

cd client
npm i

cd ..
npm start

Overview

create-react-app configures a Webpack development server to run on localhost:3000. This development server will bundle all static assets located under client/src/. All requests to localhost:3000 will serve client/index.html which will include Webpack's bundle.js.

To prevent any issues with CORS, the user's browser will communicate exclusively with the Webpack development server.

Inside Client.js, we use Fetch to make a request to the API:

// Inside Client.js
return fetch(`/api/food?q=${query}`, {
  // ...
})

This request is made to localhost:3000, the Webpack dev server. Webpack will infer that this request is actually intended for our API server. We specify in package.json that we would like Webpack to proxy API requests to localhost:3001:

// Inside client/package.json
"proxy": "http://localhost:3001/",

This handy features is provided for us by create-react-app.

Therefore, the user's browser makes a request to Webpack at localhost:3000 which then proxies the request to our API server at localhost:3001:

This setup provides two advantages:

1. If the user's browser tried to request localhost:3001 directly, we'd run into issues with CORS.
2. The API URL in development matches that in production. You don't have to do something like this:

// Example API base URL determination in Client.js
const apiBaseUrl = process.env.NODE_ENV === 'development' ? 'localhost:3001' : '/'

This setup uses concurrently for process management. Executing npm start instructs concurrently to boot both the Webpack dev server and the API server.

Deploying

Background

The app is ready to be deployed to Heroku.

In production, Heroku will use Procfile which boots just the server:

web: npm run server

Inside server.js, we tell Node/Express we'd like it to serve static assets in production:

if (process.env.NODE_ENV === 'production') {
  app.use(express.static('client/build'));
}

You just need to have Webpack produce a static bundle of the React app (below).

Steps

We assume basic knowledge of Heroku.

0. Setup your Heroku account and Heroku CLI

For installing the CLI tool, see this article.

1. Build the React app

Running npm run build creates the static bundle which we can then use any HTTP server to serve:

cd client/
npm run build

2. Commit the client/build folder to source control

From the root of the project:

git add client/build
git commit -m 'Adding `build` to source control'

3. Create the Heroku app

heroku apps:create food-lookup-demo

4. Push to Heroku

git push heroku master

Heroku will give you a link at which to view your live app.