javascript - what's the technical difference between express and http, and connect for that matter

Question

var express = require("express")
  , app = express()
  , http = require("http").createServer(app)

I constantly see these being put on the dependencies. From my point of understanding, http hosts front-end html? and express holds server-sided nodejs logic? and connect was the base layer of express so is that also a server-sided module?

If that's not the case why not people just do

express().listen(8080)

instead of

require("http").createServer(express()).listen(8080)

Answer 1

Express is another layer on top of http. It takes care of basic repeated tasks that are required for an web application. connect is a middleware, which too takes care of basic repeated tasks that are required for an web application.

The whole idea, behind using any framework is to stay DRY, Don't Repeat Yourself. Tasks like, parsing the body of the request, parsing cookies are very much required for every web-application. Express provides them by default.

In the Express 4.x, most of it has been refactored in to several granular modules, like body-parser, morgan etc. One can use them directly without using express. Please refer Express - GitHub for complete set of modules.

Express is another layer on top of http means Express internally uses http. In other words, it is a wrapper over http. If you look at the source code of Express, you will find that it internally uses http. Please refer the highlighted statements at https://github.com/strongloop/express/blob/master/lib/application.js#L540-543