Tuesday, May 29, 2012

Current commonly accepted best practices around code organization in JavaScript

As JavaScript frameworks like jQuery make client side web applications richer and more functional, I've started to notice one problem...

How in the world do you keep this organized?

  • Put all your handlers in one spot and write functions for all the events?

  • Create function/classes to wrap all your functionality?

  • Write like crazy and just hope it works out for the best?

  • Give up and get a new career?

I mention jQuery, but it's really any JavaScript code in general. I'm finding that as lines upon lines begin to pile up, it gets harder to manage the script files or find what you are looking for. Quite possibly the biggest propblems I've found is there are so many ways to do the same thing, it's hard to know which one is the current commonly accepted best practice.

Are there any general recommendations on the best way to keep your .js files as nice and neat as the rest of your application? Or is this just a matter of IDE? Is there a better option out there?


This question was intended to be more about code organization and not file organization. There has been some really good examples of merging files or splitting content around.

My question is: what is the current commonly accepted best practice way to organize your actual code? What is your way, or even a recommended way to interact with page elements and create reuseable code that doesn't conflict with each other?

Some people have listed namespaces which is a good idea. What are some other ways, more specifically dealing with elements on the page and keeping the code organized and neat?

Source: Tips4all


  1. It would be a lot nicer if javascript had namespaces built in, but I find that organizing things like Dustin Diaz describes here helps me a lot.

    var DED = (function() {

    var private_var;

    function private_method()
    // do stuff here

    return {
    method_1 : function()
    // do stuff here
    method_2 : function()
    // do stuff here

    I put different "namespaces" and sometimes individual classes in separate files. Usually I start with one file and as a class or namespace gets big enough to warrant it, I separate it out into its own file. Using a tool to combine all you files for production is an excellent idea as well.

  2. I try to avoid including any javascript with the HTML. All the code is encapsulated into classes and each class is in its own file. For development, I have separate <script> tags to include each js file, but they get merged into a single larger package for production to reduce the overhead of the HTTP requests.

    Typically, I'll have a single 'main' js file for each application. So, if I was writing a "survey" application, i would have a js file called "survey.js". This would contain the entry point into the jQuery code. I create jQuery references during instantiation and then pass them into my objects as parameters. This means that the javascript classes are 'pure' and don't contain any references to CSS ids or classnames.

    // file: survey.js
    $(document).ready(function() {
    var jS = $('#surveycontainer');
    var jB = $('#dimscreencontainer');
    var d = new DimScreen({container: jB});
    var s = new Survey({container: jS, DimScreen: d});

    I also find naming convention to be important for readability. For example: I prepend 'j' to all jQuery instances.

    In the above example, there is a class called DimScreen. (Assume this dims the screen and pops up an alert box.) It needs a div element that it can enlarge to cover the screen, and then add an alert box, so I pass in a jQuery object. jQuery has a plug-in concept, but it seemed limiting (e.g. instances are not persistent and cannot be accessed) with no real upside. So the DimScreen class would be a standard javascript class that just happens to use jQuery.

    // file: dimscreen.js
    function DimScreen(opts) {
    this.jB = opts.container;
    // ...
    }; // need the semi-colon for minimizing!

    DimScreen.prototype.draw = function(msg) {
    var me = this;

    I've built some fairly complex appliations using this approach.

  3. You can break up your scripts into separate files for development, then create a "release" version where you cram them all together and run YUI Compressor or something similar on it.

  4. Inspired by earlier posts I made a copy of Rakefile and vendor directories distributed with WysiHat (a RTE mentioned by changelog) and made a few modifications to include code-checking with JSLint and minification with YUI Compressor.

    The idea is to use Sprockets (from WysiHat) to merge multiple JavaScripts into one file, check syntax of the merged file with JSLint and minify it with YUI Compressor before distribution.


    Java Runtime
    ruby and rake gem
    You should know how to put a JAR into Classpath

    Now do

    Download Rhino and put the JAR ("js.jar") to your classpath
    Download YUI Compressor and put the JAR (build/yuicompressor-xyz.jar) to your classpath
    Download WysiHat and copy "vendor" directory to the root of your JavaScript project
    Download JSLint for Rhino and put it inside the "vendor" directory

    Now create a file named "Rakefile" in the root directory of the JavaScript project and add the following content to it:

    require 'rake'

    ROOT = File.expand_path(File.dirname(__FILE__))
    OUTPUT_MERGED = "final.js"
    OUTPUT_MINIFIED = "final.min.js"

    task :default => :check

    desc "Merges the JavaScript sources."
    task :merge do
    require File.join(ROOT, "vendor", "sprockets")

    environment = Sprockets::Environment.new(".")
    preprocessor = Sprockets::Preprocessor.new(environment)

    %w(main.js).each do |filename|
    pathname = environment.find(filename)

    output = preprocessor.output_file
    File.open(File.join(ROOT, OUTPUT_MERGED), 'w') { |f| f.write(output) }

    desc "Check the JavaScript source with JSLint."
    task :check => [:merge] do
    jslint_path = File.join(ROOT, "vendor", "jslint.js")

    sh 'java', 'org.mozilla.javascript.tools.shell.Main',
    jslint_path, OUTPUT_MERGED

    desc "Minifies the JavaScript source."
    task :minify => [:merge] do
    sh 'java', 'com.yahoo.platform.yui.compressor.Bootstrap', '-v',

    If you done everything correctly, you should be able to use the following commands in your console:

    rake merge -- to merge different JavaScript files into one
    rake check -- to check the syntax of your code (this is the default task, so you can simply type rake)
    rake minify -- to prepare minified version of your JS code

    On source merging

    Using Sprockets, the JavaScript pre-processor you can include (or require) other JavaScript files. Use the following syntax to include other scripts from the initial file (named "main.js", but you can change that in the Rakefile):

    (function() {
    //= require "subdir/jsfile.js"
    //= require "anotherfile.js"

    // some code that depends on included files
    // note that all included files can be in the same private scope

    And then...

    Take a look at Rakefile provided with WysiHat to set the automated unit testing up. Nice stuff :)

    And now for the answer

    This does not answer the original question very well. I know and I'm sorry about that, but I've posted it here because I hope it may be useful to someone else to organize their mess.

    My approach to the problem is to do as much object-oriented modelling I can and separate implementations into different files. Then the handlers should be as short as possible. The example with List singleton is also nice one.

    And namespaces... well they can be imitated by deeper object structure.

    if (typeof org !== 'undefined') {
    var org = {};

    if (!org.hasOwnProperty('example')) {
    org.example = {};

    org.example.AnotherObject = function () {
    // constructor body

    I'm not big fan of imitations, but this can be helpful if you have many objects that you would like to move out of the global scope.

  5. I was able to successfully apply the Javascript Module Pattern to an Ext JS application at my previous job. It provided a simple way to create nicely encapsulated code.

  6. Following good OO design principals and design patterns goes a long way to making your code easy to maintain and understand.
    But one of the best things I've discovered recently are signals and slots aka publish/subscribe.
    Have a look at http://markdotmeyer.blogspot.com/2008/09/jquery-publish-subscribe.html
    for a simple jQuery implementation.

    The idea is well used in other languages for GUI development. When something significant happens somewhere in your code you publish a global synthetic event which other methods in other objects may subscribe to.
    This gives excellent separation of objects.

    I think Dojo (and Prototype?) have a built in version of this technique.

    see also http://stackoverflow.com/questions/312895/signals-and-slots

  7. Dojo had the module system from the day one. In fact it is considered to be a cornerstone of Dojo, the glue that holds it all together:

    dojo.require — the official doc.
    Understanding dojo.declare, dojo.require, and dojo.provide.
    Introducing Dojo.

    Using modules Dojo achieves following objectives:

    Namespaces for Dojo code and custom code (dojo.declare()) — do not pollute the global space, coexist with other libraries, and user's non-Dojo-aware code.
    Loading modules synchronously or asynchronously by name (dojo.require()).
    Custom builds by analyzing module dependencies to create a single file or a group of interdependent files (so-called layers) to include only what your web application needs. Custom builds can include Dojo modules and customer-supplied modules as well.
    Transparent CDN-based access to Dojo and user's code. Both AOL and Google carry Dojo in this fashion, but some customers do that for their custom web applications as well.

  8. The code organization requires adoption of conventions and documentation standards:
    1. Namespace code for a physical file;

    Exc = {};

    2. Group classes in these namespaces javascript;
    3. Set Prototypes or related functions or classes for representing real-world objects;

    Exc = {};
    Exc.ui = {};
    Exc.ui.maskedInput = function (mask) {
    this.mask = mask;
    Exc.ui.domTips = function (dom, tips) {
    this.dom = gift;
    this.tips = tips;

    4. Set conventions to improve the code. For example, group all of its internal functions or methods in its class attribute of an object type.

    Exc.ui.domTips = function (dom, tips) {
    this.dom = gift;
    this.tips = tips;
    this.internal = {
    widthEstimates: function (tips) {
    formatTips: function () {

    5. Make documentation of namespaces, classes, methods and variables. Where necessary also discuss some of the code (some FIs and Fors, they usually implement important logic of the code).

    * Namespace <i> Example </i> created to group other namespaces of the "Example".
    Exc = {};
    * Namespace <i> ui </i> created with the aim of grouping namespaces user interface.
    Exc.ui = {};

    * Class <i> maskdInput </i> used to add an input HTML formatting capabilities and validation of data and information.
    * @ Param {String} mask - mask validation of input data.
    Exc.ui.maskedInput = function (mask) {
    this.mask = mask;

    * Class <i> domTips </i> used to add an HTML element the ability to present tips and information about its function or rule input etc..
    * @ Param {String} id - id of the HTML element.
    * @ Param {String} tips - tips on the element that will appear when the mouse is over the element whose identifier is id <i> </i>.
    Exc.ui.domTips = function (id, tips) {
    this.domID = id;
    this.tips = tips;

    These are just some tips, but that has greatly helped in organizing the code. Remember you must have discipline to succeed!

  9. Check out JavasciptMVC.

    You can :

    split up your code into model, view and controller layers.
    compress all code into a single production file
    auto-generate code
    create and run unit tests
    and lots more...

    Best of all, it uses jQuery, so you can take advantage of other jQuery plugins too.

  10. My boss still speaks of the times when they wrote modular code (C language), and complains about how crappy the code is nowadays! It is said that programmers can write assembly in any framework. There is always a strategy to overcome code organisation. The basic problem is with guys who treat java script as a toy and never try to learn it.

    In my case, I write js files on a UI theme or application screen basis, with a proper init_screen(). Using proper id naming convention, I make sure that there are no name space conflicts at the root element level. In the unobstrusive window.load(), I tie the things up based on the top level id.

    I strictly use java script closures and patterns to hide all private methods. After doing this, never faced a problem of conflicting properties/function definitions/variable definitions. However, when working with a team it is often difficult to enforce the same rigour.

  11. I'm surprised no one mentioned MVC frameworks. I've been using Backbone.js to modularize and decouple my code, and it's been invaluable.

    There are quite a few of these kinds of frameworks out there, and most of them are pretty tiny too. My personal opinion is that if you're going to be writing more than just a couple lines of jQuery for flashy UI stuff, or want a rich Ajax application, an MVC framework will make your life much easier.

  12. I create singletons for every thing I really do not need to instantiate several times on screen, a classes for everything else. And all of them are put in the same namespace in the same file. Everything is commented, and designed with UML , state diagrams. The javascript code is clear of html so no inline javascript and I tend to use jquery to minimize cross browser issues.

  13. "Write like crazy and just hope it works out for the best?", I've seen a project like this which was developed and maintained by just 2 developers, a huge application with lots of javascript code. On top of that there were different shortcuts for every possible jquery function you can think of. I suggested they organize the code as plugins, as that is the jquery equivalent of class, module, namespace... and the whole universe. But things got much worse, now they started writing plugins replacing every combination of 3 lines of code used in the project.
    Personaly I think jQuery is the devil and it shouldn't be used on projects with lots of javascript because it encourages you to be lazy and not think of organizing code in any way. I'd rather read 100 lines of javascript than one line with 40 chained jQuery functions (I'm not kidding).
    Contrary to popular belief it's very easy to organize javascript code in equivalents to namespaces and classes. That's what YUI and Dojo do. You can easily roll your own if you like. I find YUI's approach much better and efficient. But you usualy need a nice editor with support for snippets to compensate for YUI naming conventions if you want to write anything useful.

  14. A few days ago, the guys at 37Signals released a RTE control, with a twist. They made a library that bundles javascript files using a sort of pre-processor commands.

    I've been using it since to separate my JS files and then in the end merge them as one. That way I can separate concerns and, in the end, have only one file that goes through the pipe (gzipped, no less).

    In your templates, check if you're in development mode, and include the separate files, and if in production, include the final one (which you'll have to "build" yourself).

  15. In my last project -Viajeros.com- I've used a combination of several techniques. I wouldn't know how to organize a web app -- Viajeros is a social networking site for travellers with well-defined sections, so it's kind of easy to separate the code for each area.

    I use namespace simulation and lazy loading of modules according to the site section. On each page load I declare a "vjr" object, and always load a set of common functions to it (vjr.base.js). Then each HTML page decides which modules need with a simple:

    vjr.Required = ["vjr.gallery", "vjr.comments", "vjr.favorites"];

    Vjr.base.js gets each one gzipped from the server and executes them.

    vjr.include = function(moduleList) {
    if (!moduleList) return false;
    for (var i = 0; i < moduleList.length; i++) {
    if (moduleList[i]) {
    type: "GET", url: vjr.module2fileName(moduleList[i]), dataType: "script"

    Every "module" has this structure:

    vjr.comments = {}

    vjr.comments.submitComment = function() { // do stuff }
    vjr.comments.validateComment = function() { // do stuff }

    // Handlers
    vjr.comments.setUpUI = function() {
    // Assign handlers to screen elements

    vjr.comments.init = function () {
    // initialize stuff


    Given my limited Javascript knowledge, I know there must be better ways to manage this, but until now it's working great for us.

  16. Organising your code in a Jquery centric NameSpace way may look as follows... and will not clash with other Javascript API's like Prototype, Ext either.

    <script src="jquery/1.3.2/jquery.js" type="text/javascript"></script>
    <script type="text/javascript">

    var AcmeJQ = jQuery.noConflict(true);
    var Acme = {fn: function(){}};


    Acme.sayHi = function()

    Acme.sayBye = function()
    console.log('Good Bye');

    // Usage
    // Acme.sayHi();
    // or
    // <a href="#" onclick="Acme.sayHi();">Say Hello</a>


    Hope this helps.

  17. I use Dojo's package management (dojo.require and dojo.provide) and class system (dojo.declare which also allows for simple multiple inheritance) to modularize all of my classes/widgets into separate files. Not only dose this keep your code organized, but it also lets you do lazy/just in time loading of classes/widgets.

  18. Create fake classes, and make sure that anything that can be thrown into a separate function that makes sense is done so. Also make sure to comment a lot, and not to write spagghetti code, rather keeping it all in sections. For example, some nonsense code depicting my ideals. Obviously in real life I also write many libraries that basically encompass their functionality.

    //Preload header images

    //Create new datagrid
    var dGrid = datagrid.init({width: 5, url: 'datalist.txt', style: 'aero'});

    var datagrid = {
    init: function(w, url, style){
    //Rendering code goes here for style / width
    //code etc

    //Fetch data in
    $.get(url, {}, function(data){
    data = data.split('\n');
    for(var i=0; i < data.length; i++){
    //fetching data
    refresh: function(deep){
    //more functions etc.