Answers for "what is cors used for node js"

express js cors

var express = require('express')
var cors = require('cors')  //use this
var app = express()

app.use(cors()) //and this

app.get('/user/:id', function (req, res, next) {
  res.json({user: 'CORS enabled'})
})

app.listen(5000, function () {
  console.log('CORS-enabled web server listening on port 5000')
})

cors npm

/* 
Installation
$ npm install cors
*/

// Simple Usage (Enable All CORS Requests)
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(3000, function () {
   console.log("CORS-enabled web server listening on port 3000");
});

nodejs CORS policy

app.use(function(req, res, next) {
  res.header("Access-Control-Allow-Origin", "YOUR-DOMAIN.TLD"); // update to match the domain you will make the request from
  res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
  next();
});

app.get('/', function(req, res, next) {
  // Handle the get for this route
});

app.post('/', function(req, res, next) {
 // Handle the post for this route
});

cors npm

installation :

$ npm i cors

usage :

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')
})

add express and cors to nodejs app

/*index.js*/                                                         
const express = require( 'express' );                                                             
const cors = require( 'cors' );
const app = express();                                                                                          const port = 3030;
//cors is enabled through out the entire app                                                                                  
app.use( cors() );
app.get( '/users', (request, response, next) => {                                                                                                                                                                                                                                                                            res.json( { info: 'cors is enabled' } )                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        });
app.listen( port, () => {                                                              
  console.log(`App is running on ${port}`)                                                      
  });

express js cors

//Cors = Cross-origin resource sharing

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

app.use(cors());

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

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