Node Tutorial Part 15: Node Versions, npm Publishing

28 Feb 2011 | By Alex Young | Tags server node tutorials lmawa nodepad npm

Welcome to part 15 of Let’s Make a Web App, a tutorial series about building a web app with Node. This series will walk you through the major areas you’ll need to face when building your own applications. These tutorials are tagged with lmawa.

Previous tutorials:

Switching Node Versions

People are starting to send in error reports when they try to run Nodepad with Node 0.4.×. I’ll migrate it to support that version soon, but before that we have a few loose ends to tie up. However, I realise that waiting a few weeks for me to catch up is annoying, so in the meantime I’ll demonstrate how to easily switch between versions of Node.

I’m going to use n to do this. It can be installed with:

npm install n

I still have Node 0.2.4 on my desktop where I write DailyJS articles. That version is pretty old now. Let’s switch to 0.2.6 using n:

n 0.2.6

It might take a while to build Node on your system, just about long enough to make a coffee.

Now node -v should show v0.2.6.

Publishing Packages with npm

jamesm-sitegen asked us if we could publish Nodepad to npm. It’s actually very easy to do this, so easy it isn’t even worth a full tutorial.

The key thing to know is npm comes with lots of man pages. If you’d like to work with npm and publish packages, npm-developers is like a getting started guide. Type:

man npm-developers

to read it. Another useful man page is npm-adduser which tells you how to register yourself with npm. The npm adduser command can be used to create a new account to publish packages, or to simply use existing credentials to add another computer. Just type:

npm adduser

and follow the prompts. The email address and other details will be stored in ~/.npmrc.

Next you need to write a package.json which fortunately isn’t too hard. You could copy an existing one from another project like Nodepad, but make sure you type man npm-json and learn the basics for yourself first.

Once you’ve got a file you’re happy with you can do a local dry-run before publishing the package:

npm install .

Publishing for real is easy. Run this from your project:

npm publish

To confirm it was published, I typed this:

npm ls nodepad

And I saw the following (notice the remote flag):

nodepad@0.0.1   A notepad written with Node    =alexyoung installed latest remote

Making Binaries

Even better, we can make a little wrapper to allow people to launch Nodepad. I’ve added this to bin/nodepad.js:

#!/usr/bin/env node
var app = require('../app.js');
app.listen(3000);

And then in package.json I’ve got this:

"bin": {
  "nodepad": "bin/nodepad.js"
}

The launcher script just requires our Express app — npm will wrap everything so the paths make sense. When writing binaries, use paths relative to bin/.

Conclusion

When following random tutorials written by gnarly old programmers on the Internet, it’s a good idea to pay attention to the version of everything in your environment. If your scripting language isn’t the same version, the tutorial probably won’t make sense. Tools like n make it easy for us Node programmers to switch between versions of Node without any fuss.

And publishing with npm is easy, you don’t even need to leave your shell.

The latest commit is 89abea1


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