express app server . listen all interfaces instead of localhost only

document: app.listen([port[, host[, backlog]]][, callback])

example:

const express = require('express');
const app = express();
app.listen('9000','0.0.0.0',()=>{
      console.log("server is listening on 9000 port");
})

Note: 0.0.0.0 to be given as host in order to access from outside interface

From the documentation: app.listen(port, [hostname], [backlog], [callback])

Binds and listens for connections on the specified host and port. This method is identical to Node’s http.Server.listen().

var express = require('express');
var app = express();
app.listen(3000, '0.0.0.0');

If you don't specify host while calling app.listen, server will run on all interfaces available i.e on 0.0.0.0

You can bind the IP address using the following code

app.listen(3000, '127.0.0.1');

If you want to run server in all interface use the following code

app.listen(3000, '0.0.0.0');

or

app.listen(3000)