MERN Stack - Express and React on same port?

Question

I'm working on a project with the MERN (MongoDB, Express, React, Node) stack and I'm having issues when posting data from a form within a React component to an API endpoint defined in Node.js. When I submit the form the browser just shows a CANNOT POST error. I'm pretty confident that if I create an event handler for the form submit within React and handle the POST using a library such as Axios that I could get around this issue.

But ultimately I believe this problem is because the Node backend is running on a different port to the React front end. Is there a way that I can configure my stack so I can use a standard form POST and potentially have the FE and BE running on the same port?

Answer 1

I see that you are running an un-ejected CRA. That means that when you run npm run start from your create-react-app folder you should have react running on port 3000, the default port.

First I would recommend keeping your server and client code into a separate folder with separate package.json files

Now let suppose you have this code in /server/index.js Its straight out of the express example but the route starts with /api and also will run on port 5000. This is very important and you will see why in a minute.

const express = require('express');
const app = express();

app.get('/api/hello', (req, res) => res.send('Hello World!'))

app.listen(5000, () => console.log('Example app listening on port 5000!'))

Now back into your /client folder where I will assume your CRA is, open package.json and add the following lines:

"proxy": {
  "/api/*": {
    "target": "http://localhost:5000"
  }
},

Try now to do a call the server from react with axios for example:

const helloFromApi = 
  axios
    .get('/api/hello')
    .then(res => res.data);

Hope it helps

UPDATE 10/21/2019

proxy field in package.json must be a string

"proxy": "http://localhost:5000"

Answer 2

For developing add the following line to the package.json file

"proxy": "http://localhost:{your API port}/"

For production you can setup proxying in app (Express, Nginx, ...) which will serve your static files (React app, styles, etc). Usually using "/api/" mask for determination API request.

Answer 3

I know this is late to answer but could be helpful for anyone looking for one more solution. This solution could be applied for a react application or a angular application with a node backend at same port and if you are creating your image with the help of Docker.

So whenever you are deploying your project at production level. Just build your angular or react project with the help of npm run build and in your express app just serve the whole build folder with the help of express static.

So your Docker file could be something like this

# The builder from node image
FROM node:8-alpine as web-app

# Move our files into directory name "app"
WORKDIR /app
COPY package.json /app/
RUN cd /app && npm install
COPY . /app
RUN cd /app && npm run build  // build your front end

EXPOSE 5000

CMD [ "node", "server.js" ] // start your backend

This will start the backend on port 5000.

Now in app.js file or wherever you have your server file in express of yours, serve the build folder like this

app.use(express.static(path.join(__dirname, 'build')))

If you want to test it in your local. You can create above docker file and change the app.js as shown above to serve static files. And then build and start the docker image like this

docker build . -t web-app
docker run -p 5000:5000 web-app

Now your front end gets build at production level and served from express.

Remember in local you can always start both ports for development and use the feature provided by react or angular like auto reloading after changes in your front end and make development easy.

Answer 4

But ultimately I believe this problem is because the Node backend is running on a different port to the React front end.

Okay,

MERN is fantastic. My only problem was I couldn't use Mongoose on the React side, I came across this issue and after a few hours, I found a better solution,

No need to put anything on package.json, no need to worry about CORS,

here's a working example of a user registration using mongoose (mongoose will never run on client side, don't waste time, the library modification is time consuming),

start your express server on a port, lets say 3030, and React runs on 3000,

on React side,

constructor(){ 
...
  this.server = server || 'https://my.ip.add.ress:3030'
...
}

register(username, password, signup = true) { 
return this.fetch(`${this.server}/server/register`, {
            method: 'POST',
            headers: {
                'Accept': 'application/json',
                'Content-Type': 'application/json'
            },
            body: JSON.stringify({
                username,
                password,
                signup
            })
        }).then(res => { console.log(res);
            this.setToken(res.token) // Setting the token in localStorage
            return Promise.resolve(res);
        })
}

On Node.JS server (express) side,

Create a folder 'server' and create a file server.js,

var MongoNode   = require('mongoosenode')   // I created this package for just to test mongoose which doesn't run on React side, 
var cors        = require('cors');  //use cors for cross-site request

var options = {
        key     : fs.readFileSync('server.key'),
        cert    : fs.readFileSync('server.cert'),
    };

    /*
     * Cors Options
     */ 
    var whitelist = config.allowedOrigins //put https://my.ip.add.ress:3000 in the allowedOrigins array in your config file
    var corsOptions = {
        origin: function (origin, callback) {
            if (whitelist.indexOf(origin) !== -1) {
                callback(null, true)
            } else {
                callback(new Error('Not allowed by CORS'))
            }
        }
    }
    //specify the port
    var https_port = config.server.port || 3030;

    //use app or any route included to server.js
     app.post('/register', cors(corsOptions),function(req, res) {
        //Process requests
        console.log(req.body);  //see if request payload popping up
        var mn = new MongoNode('mongodb://username:password@127.0.0.1:27017/databasename')

        var user = mn.retrieveModel('User','User').then(async(res) => { 
           try { 
             user = res.model;
              console.log(user);
              user.username = req.body.username
              user.password = req.body.password
              user.token = token_str  //jwt web token to save browser cookie 
              user.save(function(err) {
                 if (err) throw err;
                 console.log('user saved successfully');
                 res.json({ success: true, token: user.token});
              });                  

           }catch(e) { 
             console.log(e);
           }
        })

        user.save(function(err) {
            if (err) throw err;
            //console.log('user saved successfully');
            res.json({ success: true , message: 'user saved successfully', token : user.token });
        });

    }

Voila! it's done easily after a few hours of reading.

Answer 5

This is probably what you want:

https://mty-tidjani.medium.com/deploy-nodejs-react-app-on-a-single-port-domain-54a40f1abe16

To summarize, you can set up express to serve the React app as static content from a subdirectory of the server tree. This is the only way I've been able to find to get all content served over a single port, but there may be others. Likely the concept is the same since, as others have mentioned, you can't have two services sharing the same port.