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Node.js Basics

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Hello World

3:32 with Reggie Williams

Now that you have an idea of what Node.js can do, try executing JavaScript code from the command line.

Commands

Running a node application

node <filename>

Running the node REPL (Read-Eval-Print-Loop)

node

To exit the REPL use CTRL+D once or CTRL+C twice.

The code . command

In the video you see Reggie opening up his VS code using the code . command. In order to use this you'll have to enable this option in VS code first.

Inside VS code open up the Command Pallet with ctrl/cmd + shift + p or by navigating to view => Command Palette. Then search for shell and you should be presented with the option Shell Command: Install 'code' command PATH.

After clicking that option and refreshing your terminal the code command will be available.

Documentation

Node.js Installation

If you'd rather work in your own IDE you can install Node.js from the Node.js website. We suggest downloading the LTS version.

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    Who says back-end programs can't be interactive? 0:00
    In this program, we'll learn different ways to give input and output with Node. 0:03
    One way we can do this is by using the REPL. 0:08
    This stands for read-evaluate-print loop. 0:10
    The REPL is an interactive programming environment that can read our input, 0:13
    evaluate its meaning, print out feedback, and loop over this process as needed. 0:18
    Node can function as a REPL with a single command. 0:24
    Node is terminal based, so open up your terminal to try out the Node REPL. 0:27
    If you're using workspaces, Node will already be installed. 0:32
    We'll type Node, a caret or greater than symbol should appear. 0:36
    And now you can write JavaScript code that Node will interpret and respond to. 0:41
    Remember, JavaScript has the ability to do math. 0:46
    We can enter an equation in the REPL and get our answer. 0:49
    Let's try something really hard. 0:53
    2 + 2, Node already knows that the answer is 4. 0:57
    We can also define variables. 1:02
    Use let favoriteMovie, 1:04
    make sure I use proper camelCase, 1:08
    I'm gonna type in favoriteMovie again, I get the value 'lionKing'. 1:19
    We don't have a DOM to work with. 1:24
    But remember those host objects. 1:26
    Node has host objects including its own version of the console object. 1:29
    We can console.log, our favorite movie variable, 1:34
    and it prints out the value lionKing to the console or terminal. 1:44
    Input and output like this shows us some of the capabilities of Node. 1:49
    But one thing that makes Node great is its ability to run programs in JavaScript files. 1:53
    With Node we can execute a program using the node command followed by the name of 1:59
    the program. 2:04
    Let's create a directory with the mkdir keyword. 2:06
    And we should probably first exit the REPL, by pressing Ctrl + C twice. 2:13
    Now again, we'll create a directory named nodePractice. 2:24
    Change into that directory. 2:31
    And we'll open up visual studio code to start writing our files. 2:38
    We'll create an app.js file. 2:43
    And inside the file, we'll type console.log. 2:48
    Our favorite programming phrase, ("Hello World") and save. 2:58
    Back in the console, you can type node app.js, 3:05
    and Hello World is printed out to the console. 3:10
    Node can do a lot more than just print messages to the screen. 3:15
    You've just learned two ways we can use Node to work with JavaScript outside of 3:18
    the browser. 3:22
    And this is a tiny sample of what Node is capable of doing. 3:23
    We'll learn about more tasks like connecting to an API, and 3:26
    retrieving useful information in the next steps. 3:29

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