Chapter 1: Introduction to the MEAN Stack

Activity 1: Creating an HTTP Server for a Blogging Application

1. Create a new folder at an appropriate location in your system and rename it Blogging Application.

   Open the newly created Blogging Application folder from your code editor (Visual Studio) and create a server.js file, as shown in the following screenshot:

   

   Figure 1.19: Creating the server.js file

2. Declare and assign HTTP using the following command:

   var http = require ('http'); 

3. Declare and assign the hostname and port number:

   const hostname = '127.0.0.1';
   const port = 8000; 

4. Create the HTTP server:

   const server = http.createServer((req, res) => {
   res.statusCode = 200;
   res.setHeader('Content-Type', 'text/plain');
   res.end('Blogging Application\n');});

5. Call the server to listen to localhost on the specified port:

   server.listen(port, hostname, () => {
   console.log ('Server running at
   http://${hostname}:${port}/');});

6. Run the server by first pressing Ctrl + to open the integrated command-line terminal in Visual Studio and then type the following:

   >node server.js

   You will obtain the following output:

   

   Figure 1.20: Running the server on the command-line interface

7. Go to your browser and type http://localhost:3000 in the URL address bar. You should obtain the following output:

   

   Figure 1.21: Final output of the activity

Activity 2: Streaming Data to a File

1. Go to your Desktop and create a new folder and rename it StreamingProgram.

2. Open the newly created StreamingPrgram folder from your code editor (Visual Studio) and create stream.js, readTextFile.txt, and writeTextFile.txt, as shown here:

   

   Figure 1.22: Creating the streaming program files

3. Load and import the filesystem module into the stream.js file using the following code:

   var fs = require('fs');

4. Create a readable stream by calling the createReadStream() function on the readTextFile.txt file using the following code:

   Const readableStream = fs.createReadStream('readTextFile.txt');

5. Create a writable stream by calling the createWriteStream() function on the writeTextFile.txt file using the following code:

   Const writableStream = fs.createWriteStream('writeTextFile.txt');

6. Call the on() function on the readableStream() method. Then, pass data as the first argument and then attach a callback, as shown in the following code:

   readableStream.on('data', function (data) {
   console.log('Hey!, I am about to write what has been read from this file readTextFile.txt');
   });

7. Call the write() method on the writeableStream() method to write data inside the readableStream() callback using the following code:

   readableStream.on('data', function (data) {
   console.log('Hey!, am about to write what has been read from this file readTextFile.txt');
   var txt = ' Written!' 
       var newdata = data + txt; //Append text string to the read data
       if (writableStream.write(newdata) === true) {
       console.log('Hey!, am done writing, Open the file writeTextFile.txt to see what has been written');
           }
       else
       console.log('Writing is not successful');
   });

8. Press Ctrl+ to open the integrated command-line terminal in Visual Studio and run the program by typing in the following code:

   node stream.js

   You will obtain the following output:

   

   Figure 1.23: Running the streaming program

   Then, open the writeTextFile.txt file to confirm the text that was read and written into it.