How to enable cors nodejs with express?

Question

In summary I am using a viewer like api of dicom files called cornerstone, for this I connect to the WADO service of dc4chee to get the dicom, dcm4chee runs port 8080, and my application on node uses port 3000, so I am trying to show The browser's dicom.

https://www.npmjs.com/package/cornerstone-wado-image-loader

This is the error displayed by the browser

XMLHttpRequest can not load http: // localhost: 8080 / wado? RequestType = WADO & studyUID = 1.2.840.113704.1.111.5 ... 26513.429 & contentType = application% 2Fdicom & transferSyntax = 1.2.840.10008.1.2. In 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http: // localhost: 3000' is therefore not allowed access.

In the documentation specified

Note that the web server must support Cross source resource sharing or the image will fail to load. If you are unable to get CORS enabled on the web server you are loading DICOM P10 instances from, you can use a reverse proxy. Here's a simple Node.js based on http-proxy that adds CORS headers that you might find useful.

And show this example code but I'm using express and this code does not work

Var http = require ('http'),
    HttpProxy = require ('http-proxy');

Var proxy = httpProxy.createProxyServer ({target: 'http: // localhost: 8042'}) .listen (8000);

Proxy.on ('proxyRes', function (proxyReq, req, res, options) {
  // add the CORS header to the response
  Res.setHeader ('Access-Control-Allow-Origin', '*');
});

Proxy.on ('error', function (e) {
  // suppress errors
});

Also use npm cors here the code

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')
})

But with this I enable the cors on port 3000 and not the 8080, I need the mode to activate or add 'Access-Control-Allow-Origin in headers response and not in header request,

How can I do to add CORS on port 8080 where dcm4chee runs from NODEjs?

sorry for my English

update!

The server responds with the following;

RESPONDE HEADER

Content-Type:application/dicom
Date:Sat, 01 Apr 2017 01:15:38 GMT
Expires:0
Server:Apache-Coyote/1.1
Transfer-Encoding:chunked
X-Powered-By:Servlet 2.4; JBoss-4.2.3.GA (build: SVNTag=JBoss_4_2_3_GA 
date=200807181439)/JBossWeb-2.0

REQUEST HEADER

Accept:*/*
Accept-Encoding:gzip, deflate, sdch, br
Accept-Language:es-ES,es;q=0.8,en-US;q=0.6,en;q=0.4
Connection:keep-alive
Host:localhost:8080
Origin:http: //localhost:3000
Referer:http: //localhost:3000/
User-Agent:Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like 
Gecko) Chrome/55.0.2883.87 Safari/537.36

HOW TO ENABLE THE CORS IN RESPONSE HEADER??

Answer 1

To enable cors you can do this:

var cors = require('cors');
app.use(cors());
// to change your ports for different cors stuff:
app.set('port', process.env.PORT || 3000);
app.listen(app.get('port'), function() { 
  console.log('we are listening on: ', 
  app.get('port'))
});

Remember that cors are middleware, so you will want to have app.use before it so that your incoming requests will go through cors before they hit your routes.

You can change the ports depending on which one you want to use. I am pretty sure you can also replace the || with && to listen on multiple ports and set cors on those.

In raw node, I believe you have to use the writeHead, but I am not sure about the raw node implementation.

Answer 2

The error displayed by the browser means, server localhost:8080 refused a request from localhost:3000, It seems cors didn't set well on server localhost:8080.

The response header should have something like this:

Access-Control-Allow-Headers:Content-Type,Content-Length, Authorization, Accept,X-Requested-With
Access-Control-Allow-Methods:PUT,POST,GET,DELETE,OPTIONS
Access-Control-Allow-Origin:*

Try add cors header in your 8080 server.

app.all('*', function (req, res) {
    res.header("Access-Control-Allow-Origin", "*");
  res.header("Access-Control-Allow-Headers", "Content-Type,Content-Length, Authorization, Accept,X-Requested-With");
  res.header("Access-Control-Allow-Methods", "PUT,POST,GET,DELETE,OPTIONS");
//...

Answer 3

do

npm install cors --save

and just add these lines in your main file where your request is going.

const cors = require('cors');
const express = require('express');
let app = express();
app.use(cors());
app.options('*', cors());

Answer 4

Adding CORS(Cross-Origin-Resource-Sharing) to your node, express app is quite easy...

You need to install cors library via npm first, using the command below:

npm install cors -S

and if you need it globally, just add -g flag to it...

Then in your express app, do this:

const express = require('express');
const cors = require('cors');
const app = express();
app.use(cors());

Also these are other examples for cors from their doc:

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')
})

Configuring CORS Asynchronously:

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

var whitelist = ['http://example1.com', 'http://example2.com']
var corsOptionsDelegate = function (req, callback) {
  var corsOptions;
  if (whitelist.indexOf(req.header('Origin')) !== -1) {
    corsOptions = { origin: true } // reflect (enable) the requested origin in the CORS response
  }else{
    corsOptions = { origin: false } // disable CORS for this request
  }
  callback(null, corsOptions) // callback expects two parameters: error and options
}

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

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