Running Node

We install Node using the double click installer from nodejs.org, or using a package manager like brew, apt-get or aptitude.

Installation

First install Node. If you have node already you can skip this step. Type node —version into a console to find out if you have it.

If not, go on and install it.

Option 1 - install from the website

Visit nodejs.org and download the installer for your platform.

Option 2 - install via brew (OSX only)

If you’re on a Macintosh, you can install via brew. Substitute brew for aptitude, or another package manager if you prefer a different flavour of Linux.

  brew install nodejs

You may need to restart your console.

Verify node is working by typing node —version into a console. If you see a version number you have succeeded. You can type any JavaScript here.

The Node console

You can open up a NodeJS console from the command line with the node command, like so:

node;

If all is well you should drop into a console where you can type arbitrary JavaScript commands. You can do maths, create functions, assign variables, everything you can do with JavaScript.

Exercise - Node Console

Let’s try out the Node console and execute a command. Drop into the node console by typing node. Now try the following:

1. Add 10 + 10.
2. Use console.log(‘hello world’) to output hello world.
3. Find out how many seconds there are in a year. How many seconds there are in a century. I don’t know the answer to this. See, you’re smarter than me already.

Running a program

You can also run saved programs using the node command. Node files have a .js (JavaScript) suffix, like this: program.js.

We can execute our JavaScript program using node like this:

  node program.js

Exercise - Executing a program

You can make Node output to the terminal using console.log(). Create a file called app.js and add a line that uses console.log() to tell Node write “Hello World” to the console.

Run your program from the console using the node command.

You should see hello world.

Further exercise

You can find the current time using:

new Date();

Create a node program that tells you the current time and date.

You can get a date object for a specific date using:

new Date(2022, 11, 25);

You can subtract one date object from another to get the number of milliseconds between them.

dateOne - dateTwo;

Make a timeTillChristmas program that tells you how many seconds there are until Christmas.

Optionally make it tell you how many days there are.