Hints for Node.js developers using io.js on Bluemix

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If you’re interested in Node.js, but haven’t been following all the latest excitement around io.js and ECMAScript 6 (ES6), here’s the executive summary:

If you’re a current user of node.js, there’s a new kid in town named io.js. It’s a fork of node.js which is shipping with a newer version of the V8 JavaScript engine, and features available in ECMAScript 6, without having to have a special pre-release version of node.js installed, or using special node command-line flags.

Version 1.0.0 of io.js was announced and made available last night and version 1.0.1 was released about an hour later. Later I read this twitter message from Hunter Loftis:

#iojs on heroku? pic.twitter.com/tFvgx6Vuib

— Hunter Loftis (@HunterLoftis) January 14, 2015

Hunter works on the Heroku Node.js buildpack, which is the basis of the Cloud Foundry Node.js buildpack. So, it’s a good bet the Heroku buildpack will work on Bluemix too.

I gave it a try, and it just worked. Here’s the application I pushed:

https://github.com/pmuellr/bluemix-hello-iojs

It’s my usual Bluemix Hello World Node.js app, but I’ve made a few changes:

• changed manifest.yml to add the buildpack property pointing to the Heroku buildpack

• changed package.json to add a new engines property with a iojs property; this is how the buildpack determines it should use io.js instead of node.js

• changed server.js to use some new ES6 functionality:

  • using let instead of var; note you need to be running in “strict mode” to enable this—enabling strict mode is done by including the string "use strict" at the top of your file
  • using template strings instead of string concatenation.

That last feature is fun, and something I use a lot when I’m writing CoffeeScript. It’s often referred to in other programming languages as “string interpolation”. That is, instead of writing something like this:

log("request " + request.method + " "+ request.url)

you can write

log(`request ${request.method} ${request.url}`)

Check the ES6 on io.js page for more information about enabling other ES6 capabilities in your Node.js applications.