In this section we shall make our first server. The World Wide Web is a giant client/user application. In order to visualize what that the web is thus placing the frontend, the backend and the net on a visual map, we shall take a look at two diagrams:
Before we make our first test application we use npm init
to create the configuration package.json
interactively. Alter the suggested index.js
starting point to main.js. Put in some remarks
such as "First Test Application" into the description.
Finalizing that the command will present the
file content for your approval.
packakge.json
{
"name": "myg4",
"version": "1.0.0",
"description": "First Test Application",
"main": "main.js",
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1"
},
"author": "Niels Müller Larsen <nmla@iba.dk> (http://x15.dk)",
"license": "MIT"
}
Knowing one of the dependencies of the server/application we will build, let us see how to do that and get the configuration file updated in the process. On the command line we write
npm install http-status-codesor the shorter version
npm i http-status-codesThis changes the configuration
package.json
{
"name": "myg4",
"version": "1.0.0",
"description": "First Test Application",
"main": "main.js",
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1"
},
"author": "Niels Müller Larsen <nmla@iba.dk> (http://x15.dk)",
"license": "MIT",
"dependencies": {
"http-status-codes": "^1.4.0"
}
}
We will notice the added dependencies object in the
configuration.
You already saw a sneak preview of a server in so many lines of code. Now we will do it again. This time with the necessary explanatory remarks. Create an application directory, step into it and write:
myg4/main.js
"use strict";
const http = require("http");
const httpStatus = require("http-status-codes");
const hostname = "127.0.0.1";
const port = 3000;
const app = http.createServer(function (req, res) { // server obj with call back
console.log(`Received an incoming request from: ${req.url}`);
console.log(`with HTTP-method: ${req.method}`);
res.writeHead(httpStatus.OK, {
"Content-Type": "text/html; charset=utf-8"
});
let responseMsg = "<h1>Hello Universe!</h1>"; // response text
responseMsg += "<p><kbd>myg4</kbd> at your disposal</p>";
res.write(responseMsg); // response body with text
res.end(); // send http package
console.log(`My response was: ${responseMsg}`)
});
app.listen(port, hostname, function () {
console.log(`Server running, and listening at http://${hostname}:${port}/`);
});
On your CLI do node main. Then go to your
browser and do
http://localhost:3000.