Express js - app listen vs server listen

Question

This may be a very basic question but I simply don t get it  What is the difference between creating an app using Express js and starting the app listening on port 1234  for example   var express   require  express    var app   express       app configure  app use etc  app listen 1234     and adding an http server   var express   require  express    var http   require  http     var app   express    var server   http createServer app      app configure  app use etc  server listen 1234     What s the difference  If I navigate to http   localhost 1234  thus I get the same output

User · Answer

There is one more difference of using the app and listening to http server is when you want to setup for https server

To setup for https, you need the code below:

var https = require('https');
var server = https.createServer(app).listen(config.port, function() {
    console.log('Https App started');
});

The app from express will return http server only, you cannot set it in express, so you will need to use the https server command

var express = require('express');
var app = express();
app.listen(1234);

User · Answer

Express is basically a wrapper of http module that is created for the ease of the developers in such a way that     They can set up middlewares to respond to HTTP Requests  easily  using express  They can dynamically render HTML Pages based on passing arguments to templates using express  They can also define routing easily using express

User · Answer

Just for punctuality purpose and extend a bit Tim answer  From official documentation      The app returned by express   is in fact a JavaScript Function     DESIGNED TO BE PASSED to Node   s HTTP servers as a callback  to handle   requests       This makes it easy to provide both HTTP and HTTPS  versions of your   app with the same code base  as the app does not  inherit from these    it is simply a callback     http createServer app  listen 80   https createServer options  app  listen 443        The app listen   method returns an http Server object and  for HTTP    is a convenience method for the following    app listen   function       var server   http createServer this     return server listen apply server  arguments

User · Answer

The second form  creating an HTTP server yourself  instead of having Express create one for you  is useful if you want to reuse the HTTP server  for example to run socket io within the same HTTP server instance   var express   require  express    var app       express    var server    require  http   createServer app   var io        require  socket io   listen server       server listen 1234     However  app listen   also returns the HTTP server instance  so with a bit of rewriting you can achieve something similar without creating an HTTP server yourself   var express     require  express    var app         express        app use routes etc     var server      app listen 3033   var io          require  socket io   listen server    io sockets on  connection   function  socket

User · Answer

I came with same question but after google  I found there is no big difference     From Github  If you wish to create both an HTTP and HTTPS server you may do so with the  http  and  https  modules as shown here          Listen for connections        A node  http Server  is returned  with this    application  which is a  Function   as its    callback  If you wish to create both an HTTP    and HTTPS server you may do so with the  http     and  https  modules as shown here           var http   require  http             https   require  https             express   require  express             app   express             http createServer app  listen 80         https createServer          app  listen 443          return  http Server      api public      app listen   function      var server   http createServer this     return server listen apply server  arguments        Also if you want to work with socket io see their example  See this  I prefer app listen

[node.js] Express.js - app.listen vs server.listen

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