01 - NodeJS_Intro

    // NodeJS: It is a JavaScript Runtime Environment
    // =======
    //
    // After NodeJS installation, in terminal, write: node
    // Output:
    // ========
    // Welcome to Node.js v14.16.0.
    // Type ".help" for more information.
    // > .help
    // .break    Sometimes you get stuck, this gets you out
    //     .clear    Alias for .break
    //     .editor   Enter editor mode
    //     .exit     Exit the REPL
    //     .help     Print this help message
    //     .load     Load JS from a file into the REPL session
    //     .save     Save all evaluated commands in this REPL session to a file
    // 
    // Press Ctrl+C to abort current expression, Ctrl+D to exit the REPL
    //
    //---------------------------------------------------------------------------
    // Write any REPL expression:
    // ===========================
    // > 1+2+3*2+6/2+7%4 === 15
    // OUTPUT:
    // =======
    // true
    //
    // Exit the REPL mode with command: .exit
    // 
    //------------------------------------------------------------------------------
    // More Notes:
    // ===========
    // 1> For NodeJS, Global object is "global", just like "window" was for Browser
    // 2> create a dir with: mkdir 
    // 3> list out the files in the dir with: ls
    // 4> cd to change the dir: cd 
    // 5> to move out of the current dir to its parent dir: cd ..
    // 6> to remove/delete an empty dir: rm -r 
    // 7> to remove/delete non-empty dir(forcefully): rm -rf 
    // 8> to run a js file, go to the dir where the js file is present and write:
    //  > node 
    //
    //----------------------------------------------------------------------------------
    // Process: 
    // =========
    //      It is an object inside NodeJS that contains info about
    //      all the process currently running and
    //      it is also used to get the inputs from the command line.
    //      
    //      Go to REPL mode by typing: node
    //      then, write: process
    //      then, write: process.cwd();
    //      this will give you the current working directory,
    //      that is the file being run with its path.
    //
    //      Now, check below code from Index.js file below:

        console.log(process.argv);

        const arr = process.argv.slice(2);
        //in above code, 
        //process.argv returns an array whose elements, 
        //excluding the first two elements, represents the
        //input values passed as command line arguments.
        //we use slice(2) to exclude the first two elements
        //which we don't need. 

        for(let user of arr){
            console.log(`Hello from ${user}`);
        }

    // Now in terminal, exit the REPL mode( by typing, .exit), 
    // and run: node index.js Sam Ram Rahim
    // OUTPUT:
    // =======
    // [
    //    'C:\\Program Files\\nodejs\\node.exe',
    //    'E:\\Newfolder\\CSE\\Docs\\CSE\\Miscellaneous\\Study\\Web Dev\\Nagarro Bootcamp\\Web Development\\Lecture_10\\01-NodeJS_Intro\\index.js',
    //    'Sam',
    //    'Ram',
    //    'Rahim'
    // ]
    // Hello from Sam
    // Hello from Ram
    // Hello from Rahim
    //
    //--------------------------------------------------------------------------------
    //
    // Almost unrelated but, a programming problem - FizzBuzz:
    // 1- FizzBuzz.js Click here
    // 2- OptimisedFizzBuzz.js Click here