Recent javascript Posts

AngularJS Whitespace Guide

04 Dec 2013 Comments

By choice or otherwise, you may someday find yourself a slave to a strict linter. This can lead to headaches with AngularJS applications in particular because they tend to have many chained calls and functions with many arguments. While there are other guides on structuring AngularJS applications that address things like directory structure, I thought the web was lacking a guide on satisfying strict whitespace linters in AngularJS apps.

So here’s my take on formatting your AngularJS modules in a way that satisfies both JSHint and

Use Node Version Manager

19 Mar 2013 Comments

Until recently, I had been using the OSX .pkg when installing Node. I had one version installed and relied on Travis to run tests in multiple versions. I’m now totally sold on the Node Version Manager (nvm).

get it

curl | sh

use it

nvm install 0.10
nvm use 0.10

Note that you’ll likely want to uninstall your existing Node install when using nvm. If you used the OSX .pkg, you should be able to uninstall with this handy script:

After uninstalling your original Node installation, you need to tell nvm which version to use. It’s easiest to put something like nvm use 0.10 > /dev/null in your .profile or .bash_profile.

Sublime Text 2 and OpenLayers 3

15 Jan 2013 Comments

In case others are interested, here’s a nice setup for OpenLayers 3 development on OS X:

Install the Closure Linter.

sudo easy_install

Install Sublime Text 2 (register as well, its worth it). Add the Sublime Linter package (use Sublime Package Control).

Edit your user SublimeLinter.sublime-settings file (Preferences > Package Settings > SublimeLinter > Settings - User) so it looks something like the following:

/** SublimeLinter user settings */
  "sublimelinter": true,
  "sublimelinter_popup_errors_on_save": true,
  "javascript_linter": "gjslint",
  "gjslint_options": ["--strict", "--custom_jsdoc_tags=todo"],
  "gjslint_ignore": [],
  "sublimelinter_disable": ["css"]

As described in the readme, if gjslint is not on your path, you’ll need to provide the path with something like this in your user SublimeLinter.sublime-settings file:

  "sublimelinter_executable_map": {
    // your path may vary
    "javascript": "/Library/Frameworks/Python.framework/Versions/2.6/bin/gjslint"

Edit your user Preferences.sublime-settings so it includes at least the following:

  "rulers": [80],
  "tab_size": 2,
  "translate_tabs_to_spaces": true

That’s it. The biggest pain here is that you can’t have per-project package settings. So if you don’t abide by the Closure Linter in all your projects, you have to modify your user SublimeLinter.sublime-settings when changing projects (i.e. setting "sublimelinter": false).

CommonJS Modules with Rhino

17 May 2011 Comments

UPDATE: This post originally covered the syntax for using CommonJS modules with Rhino 1.7R3. I’ve updated it to cover the syntax for Rhino 1.7R4.

Rhino, Mozilla’s Java based JavaScript implementation, has gotten a facelift recently. First, the source was moved from CVS to GitHub, where it joins all the JavaScript cool kids. Let’s hope this change brings some more lifeblood into the project.

Perhaps more significantly, the 1.7R3 release of Rhino brought support for loading CommonJS modules. The nice thing about this is that you can author server-side JavaScript modules and deploy them with a single, simple dependency: a cross-platform .jar file.

To see this in action, you can download the latest release and extract the archive. For this example, I’ll write a few simple math modules that provide add and subtract methods. Then we’ll run a main.js application that pulls in these modules.

The layout for these example files looks like this:


First, here’s the add.js module:

exports.add = function(a, b) {
    return a + b;

This module doesn’t have any dependencies. It exports one method: add.

And now the subtract.js module:

var add = require("./add").add;
exports.subtract = function(a, b) {
    return add(a, -b);

For the sake of this example, the subtract.js module requires the add.js module to implement the subtract method. The require call uses a relative module locator. This makes the exports from add.js available locally.

Finally, to provide a nice API for our application to use, I’ll create a math.js module that exports both add and subtract. The math.js module looks like this:

exports.add = require("./math/add").add;
exports.subtract = require("./math/subtract").subtract;

That’s it. Now the main.js application script:

var math = require("math");
print("5 minus 3 is " + math.subtract(5, 3));

In this case, the require call uses an absolute identifier to pull in the math.js module’s exports. This means it will pull in the first math.js script found on the module search path (available as require.paths within a module).

To run my application, I invoke Rhino with the -module command line options.

$ java -jar rhino1_7R4/js.jar -modules my_modules main.js
5 minus 3 is 2

Note: With the Rhino 1.7R3 release, you needed to specify your main module with the -main option (e.g. java -jar rhino1_7R3/js.jar -modules my_modules -main main.js). The -main option is not required with 1.7R4 and later.

The -modules value is a path that becomes my module search path (use multiple -modules options for multiple paths). The last argument (main.js) is the path to my main application script.

Nothing fancy in this example, but it demonstrates the potential for scripting server-side applications with JavaScript modules using Rhino.

Older javascript Posts

Canvas Hit Detection 31 Mar 2011 Comments