OpenLMIS-UI Coding Conventions

This document describes the desired formatting to be used withing the OpenLMIS-UI repositories, many of the conventions are adapted from John Papa’s Angular V1 styleguide and SMACSS by Jonathan Snook.


The following conventions should be applied to all sections of UI development:

  • All intentation should be 4 spaces
  • Legacy code should be refactored to meet coding conventions
  • No thrid party libraries should be included in a OpenLMIS-UI repository

File Structure

All file types should be organized together within the src directory according to functionality, not file type — the goal is to keep related files together.

Use the following conventions:

  • File names are lowercase and dash-seperated
  • Files in a directory should be as flat as possible (avoid sub-directories)
  • If there are more than 12 files in a directory, try to divide files into subdirectories based on functional area

Each file type section below has specifics on their naming conventions

HTML Markup Guidelines

Less markup is better markup, and semantic markup is the best.

This means we want to avoid creating layout specific markup that defines elements such as columns or icons. Non-semantic markup can be replicated by using CSS to create columns or icons. In some cases a layout might not be possible without CSS styles that are not supported across all of our supported browsers, which is perfectly acceptiable.

Here is a common pattern for HTML that you will see used in frameworks like Twitter’s Bootstrap (which we also use)

<li class="row">
    <div class="col-md-9">
        Item Name
    <div class="col-md-3">
        <a href="#" class="btn btn-primary btn-block">
            <i class="icon icon-trash"></i>
<div class="clearfix"></div>

The above markup should be simplified to:

    Item Name
    <button class="trash">Delete</button>

This gives us simpler markup, that could be restyled and reused depending on the context that the HTML section is inserted into. We can recreate the styles applied to the markup with CSS such as:

  • A ::before pseudo class to display an icon in the button
  • Using float and width properties to correctly display the button
  • A ::after pseudo class can replace any ‘clearfix’ element (which shouldn’t exist in our code)

See the UI-Styleguide for examples of how specific elements and components should should be constructed and used.

HTML Form Markup

A goal for the OpenLMIS-UI is to keep busniess logic separated from styling, which allows for a more testable and extenable platform. Creating data entry forms is generally where logic and styling get tangled together because of the need to show error responses and validation in meaningful ways. AngularJS has built-in features to help foster this type of separation, and OpenLMIS-UI extends AngularJS’s features to a basic set of error and validation featrues.

The goal here is to attempt to keep developers and other implementers from creating their own form submission and validation - which is too easy in Javascript frameworks like AngularJS.

An ideal form in the OpenLMIS-UI would look like this:

<form name="exampleForm" ng-submit="doTheThing()">
    <label for="exampleInput">Example</label>
    <input id="exampleInput" name="exampleInput" ng-model="example" required />
    <input type="submit" value="Do Thing" />

This is a good form because:

  • There is a name attribute on the form element, which exposes the FormController
  • The input has a name attribute, which allow for validation passed to the FormController to be passed back to the correct input
  • ng-submit is used rather than ng-click on a button

Naming Convention

In general we follow the John-Papa naming conventions, later sections go into specifics about how to name a specific file type, while this section focuses on general naming and file structure.

Generally, all file names should use the following format specific-name.file-type.ext where:

  • specific-name is a dash-separated name for specific file-type
  • file-type is the type of object that is being added (ie ‘controller’, ‘service’, or ‘layout’)
  • ext is the extention of the file (ie ‘.js’, ‘.scss’)

Folder structure should aim to follow the LIFT principal as closely as possible, with a couple extra notes:

  • There should only be one *.module.js file per directory hiearchy
  • Only consider creating a sub-directory if file names are long and repatitive, such that a sub-directory would improve meaning

SASS & CSS Formatting Guidelines

General SASS and CSS conventions:

  • Only enter color values in a variables file
  • Only enter pixel or point values in a variables file
  • Variable names should be lowercase and use dashes instead of spaces (ie: $sample-variable)
  • Avoid class names in favor of child element selectors where ever possible
  • Files should be less than 200 lines long
  • CSS class names should be lowercase and use dashes instead of spaces


The CSS styles should reflect the SMACSS CSS methodology, which has 3 main sections — base, layout, and module. SMACSS has other sections and tennants, which are useful, but are not reflected in the OpenLMIS-UI coding conventions.


CSS styles applied directly to elements to create styles that are the same throughout the application.


CSS styles that are related primarly to layout in a page — think position and margin, not color and padding — these styles should never be mixed with base styles (responsive CSS should only be implemented in layout).


This is a css class that will modify base and layout styles for an element and it’s sub-elements.

SASS File-Types

Since SASS pre-processes CSS, there are 3 SCSS file types to be aware of which are processed in a specific order to make sure the build process works correctly.


A variable file is either named ‘variables.scss’ or matches ‘*.variables.scss’

Varriables files are the first loaded file type and include any variables that will be used through out the application — There should be as few of these files as possible.

The contents of a varriables file should only include SASS variables, and output no CSS at anypoint.

There is no assumed order in which varriables files will be included, which means:


A mixin file matches the following pattern *.mixin.scss

Mixins in SASS are reusable functions, which are loaded second in our build process so they can use global variables and be used in any other SCSS file.

There should only be one mixin per file, and the file name should match the function’s name, ie: ‘simple-function.mixin.scss’

All Other SCSS and CSS Files

All files that match ‘.scss’ or ‘.css’ are loaded at the same time in the build process. This means that no single file can easily overwrite another files CSS styles unless the style is more specific or uses !imporant — This creates the following conventions:

  • Keep CSS selectors as general as possible (to allow others to be more specific)
  • Avoid using !important

To keep file sizes small, consider breaking up files according to SMACSS guidelines by adding the type of classes in the file before .scss or .css (ie: navigation.layout.scss)

Javascript Formatting Guidelines

General conventions:

  • All code should be within an immedately invoked scope
  • Variable and function names should be written in camelCase
  • All Angular object names should be written in CamelCase


To document the OpenLMIS-UI, we are using ngDocs built with grunt-ngdocs. See individual object descriptions for specifics and examples of how to document that object type.

General rules

  • any object’s exposed methods or variables must be documented with ngDoc
  • @ngdoc annotation specifies the type of thing being documented
  • as ‘Type’ in documentation we should use:
  • Promise
  • Number
  • String
  • Boolean
  • Object
  • Event
  • Array
  • Scope
  • in some cases is allowed to use other types i.e. class names like Requisition
  • all description blocks should be sentence based, all of sentences should start with uppercase letter and end with ‘.’
  • before and after description block (if there is more content) there should be an empty line
  • all docs should be right above the declaration of method/property/component
  • when writing param/return section please keep all parts(type, parameter name, description) start at the same column as it is shown in method/property examples below
  • please keep the order of all parameters as it is in examples below

General Object Documentation

Regardless of the actual component’s type, it should have ‘@ngdoc service’ annotation at the start, unless the specific object documentation says otherwise. There are three annotations that must be present:

  • ngdoc definition
  • component name
  • and description
 * @ngdoc service
 * @name module-name.componentName
 * @description
 * Component description.


Methods for all components should have parameters like in the following example:

 * @ngdoc method
 * @methodOf module-name.componentName
 * @name methodName
 * @description
 * Method description.
 * @param  {Type} paramsName1 param1 description
 * @param  {Type} paramsName2 (optional) param2 description
 * @return {Type}             returned object description

Parameters should only be present when method takes any. The same rule applies to return annotation. If the parameter is not required by method, it should have “(optional)” prefix in the description.


Properties should be documented in components when they are exposed, i.e. controllers properties declared in ‘vm’. Properties should have parameters like in the following example:

 * @ngdoc property
 * @propertyOf module-name.componentName
 * @name propertyName
 * @type {Type}
 * @description
 * Property description.

Unit Testing Guidelines

A unit tests has 3 goals that it should accomplish to test a javascript object:

  • Checks success, error, and edge cases
  • Tests as few objects as possible
  • Demonstrates how an object should be used

With those 3 goals in mind, its important to realize that the variety of AngularJS object types means that the same approact won’t work for each and every object. Since the OpenLMIS-UI coding conventions layout patterns for different types of AngularJS objects, it’s also possible to illustrate how to unit test objects that follow those conventions.

Check out AngularJS’s unit testing guide, its well written and many of out tests follow their styles.

Here are some general rules to keep in mind while writing any unit tests:

  • Keep beforeEach statements short and to the point, which will help other’s read your statements
  • Understand how to use Spies in Jasmine, they can help isolate objects and provide test cases

Angular V1 Object Guidelines

AngularJS has many different object types — here are the following types the OpenLMIS-UI primarily uses. If there is a need for object types not documented, please refer to the John Papa Angular V1 styleguide.


Modules in angular should describe and bind together a small unit of functionality. The OpenLMIS-UI build process should construct larger module units from theses small units.


Docs for modules must contain the module name and description. This should be thought of as an overview for the other obects within the module, and where appropriate gives an overview of how the modules fit together.

 * @module module-name
 * @description
 * Some module description.

Replaced Values

@@ should set own default values


Constants are Javascript variables that won’t change but need to be resued between multiple objects within an Angular module. Using constants is important because it becomes possible to track an objects dependencies, rather than use variables set on the global scope.

It’s also useful to wrap 3rd party objects and libraries (like jQuery or bootbox) as an Angular constant. This is useful because the dependency is declared on the object. Another useful feature is that if the library or object isn’t included, Angualr will throw a single verbose error message.

Add rule about when its ok to add a group of constants – if a grouping of values, use a plural name


  • All constant variable names should be upper case and use underscores instead of spaces (ie VARIABLE_NAME)
  • If a constant is only relivant to a single Angular object, set it as a variable inside the scope, not as an Angular constant
  • If the constant value needs to change depending on build variables, format the value like @@VARIABLE_VALUE, and which should be replaced by the grunt build process if there is a matching value
  • Wrap 3rd party services as constants, if are not already registered with Angular


John Papa refers to services as Singletons, which means they should only be used for application information that has a single instance. Examples of this would include the current user, the application’s connection state, or the current library of localization messages.

  • Services should always return an object
  • Services shouldn’t have their state changed through properties, only method calls
Naming Convention


Always lowercase camelCase the name of the object. Append ‘Service’ to the end of the service name so developers will know the object is a service, and changes will be persisted to other controllers.

Unit Testing Conventions
  • Keep $httpBackend mock statements close to the specific places they are used (unless the statement is reusable)
  • Use Jasmine’s spyOn method to mock the methods of other objects that are used
  • In some cases mocking an entire AngularJS Service, or a constant, will be required. This is possible by using AngularJS’s $provide object within a beforeEach block. This would look like
    // mock out a tape recorder service, which is used else where
    tape = jasmine.createSpyObj('tape', ['play', 'pause', 'stop', 'rewind']);

    // overwrite an existing service
    $provide.service('TapeRecorderService', function(){
        return tape;


Factories should be the most used Angualr object type in any application. John Papa insists that factories serve a single purpose, and should be extended by variabled they are called with.

This means that factories should generally return a function that will return an object or set of objects that can be manipulated. It is common for a factory to include methods for interacting with a server, but this isn’t nessicarry.

Should be used with UI-Router resolves, and get additional arguments

Naming Convention


Factories should always be named lowercase camelCase. To avoid confussion between created objects and factories, all factories should have the word’Factory’ appended to the end (this disagrees with John-Papa style).

    .factory('sampleFactory', sample);

sample.$inject = [];
function sample(){
    var savedContext;

    return {
        method: method,
        otherMethod: otherMethod

Unit Testing Conventions Test a factory much like you would test a service, except be sure to:

  • Declare a new factory at the start of every test
  • Exercise the producted object, not just the callback function

Javascript Class

Pure javascript classes should only be used to ease the manipulation of data, but unlike factories, these object shouldn’t create HTTP connections, and only focus on a single object.

Javascript classes should be injected and used within factories and some services services that have complex logic. Modules should be able to extend javascript classes by prototypical inheritance.

Helps with code reusability

Requisition/LineItem is good example

Naming Conventions


Classes should be uppercase CamelCased, which represents that they are a class and need to be instantiated like an object (ie new SampleName()).


Controllers are all about connecting data and logic from Factories and Services to HTML Views. An ideal controller won’t do much more than this, and will be as ‘thin’ as possible.

Controllers are typically specific in context, so as a rule controllers should never be reused. A controller can be linked to a HTML form, which might be reused in multiple contexts — but that controller most likely wouldn’t be applicable in other places.

It is also worth noting that John Papa insists that controllers don’t directly manipulate properties in $scope, but rather the ControllerAs syntax should be used which injects the controller into a HTML block’s context. The main rationale is that it makes the $scope variables less cluttered, and makes the controller more testable as an object.

  • Should be only object changing application $state
  • Is used in a single context
  • Don’t use the $scope variable EVER
  • Use ControllerAs syntax
  • Don’t $watch variables, use on-change or refactor to use a directive to watch values
Unit Testing
  • Set all items that would be required from a route when the Controller is instantiated
  • Mock any services used by the controller

The only difference between controllers and other components is the ‘.controller:’ part in the @name annotation. It makes controller documentation appear in controllers section. Be sure to document the methods and properties that the controller exposes.

 * @ngdoc service
 * @name module-name.controller:controllerName
 * @description
 * Controller description.


Routing logic is defined by UI-Router, where a URL path is typically paired with an HTML View and Controller.

Use a factory where possible to keep resolve statements small and testable

General Conventions

HTTP Interceptor

HTTP Interceptors are technically factories that have been configured to ‘intercept’ certain types of requests in Angular and modify their behavior. This is recommended because other Angular objects can use consistent Angular objects, reducing the need to write code that is specialized for our own framework.

Keep all objects in a single file - so its easier to understand the actions that are being taken

The Angular guide to writting HTTP Interceptors is here

General Conventions
  • Write interceptors so they only chanage a request on certain conditions, so other unit tests don’t have to be modified for the interceptors conditions
  • Don’t include HTTP Interceptors in openlmis-core, as the interceptor might be injected into all other unit tests — which could break everything
Unit Testing Conventions

The goal when unit testing an interceptor is to not only test input and output transformation functions, but to also make sure the interceptor is called at an appropriate time.


Directives are pieces of HTML markup that have been extended to do a certain function. This is the only place where it is reasonable to manipulate the DOM.

Make disticntion between directive and component – components use E tag and isolate scope, directive use C and never isolate scope

  • Restrict directives to only elements or attributes
  • Don’t use an isolated scope unless you absolutely have to
  • If the directive needs extenal information, use a controller — don’t manipulate data in a link function
Unit Testing

The bit secrect when unit testing a directive is to make sure to use the $compile function to return an element that is extended with jQuery. Once you have this object you will be able to interact with the directive by clicking, hovering, or triggering other DOM events.

describe('SampleDirective', function(){
    it('gets compiled and shows the selected item name', function($compile, $rootScope){
        var scope = $rootScope.$new();
        scope['item'] = {
            name: "Sample Title"
        var element = $compile("<sample-directive selected='item'></sample-directive>")(scope);

        expect(element.text()).toBe("Sample Title");
    it('responds to being clicked', function($compile, $rootScope){
        var element = $compile("<sample-directive selected='item'></sample-directive>")($rootScope.$new());

        // check before the action
        expect(element.text()).toBe("No Title");;
        // check to see the results of the action
        // this could also be looking at a spy to see what the values are
        expect(element.text()).toBe("I was clicked");

Directive docs should have well described ‘@example’ section.

Directive docs should always have ‘@restrict’ annotation that takes as a value one of: A, E, C, M or any combination of those. In order to make directive docs appear in directives section there needs to be ‘.directive:’ part in @name annotation.

 * @ngdoc directive
 * @restrict A
 * @name module-name.directive:directiveName
 * @description
 * Directive description.
 * @example
 * Short description of how to use it.
 * ```
 *   <div directiveName></div>
 * ```
 * Now you can show how the markup will look like after applying directive code.
 * ```
 * <div directiveName>
 *     <div>something</div>
 * </div>
 * ```
Extending a Directive

You can extend a directive by using AngularJS’s decorator pattern. Keep in mind that a directive might be applied to multiple places or have multiple directives applied to the same element name.


extendDirective.$inject = ['$provide'];
function extendDirective($provide) {
  // NOTE: This method has you put 'Directive' at the end of a directive name
  $provide.decorator('OpenlmisInvalidDirective', directiveDecorator);

directiveDecorator.$inject = ['$delegate'];
function directiveDecorator($delegate) {
  var directive = $delegate[0], // directives are returned as an array
      originalLink =; = function(scope, element, attrs) {
    // do something
    originalLink.apply(directive, arguments); // do the original thing
    // do something after

  return $delegate;




Filter docs should follow the pattern from example below:

 * @ngdoc filter
 * @name module-name.filter:filterName
 * @description
 * Filter description.
 * @param   {Type} input     input description
 * @param   {Type} parameter parameter description
 * @return  {Type}           returned value description
 * @example
 * You could have short description of what example is about etc.
 * ```
 * <div>{{valueToBeFiltered | filterName:parameter}}</div>
 * ```

It is a good practice to add example block at the end to make clear how to use it. As for parameters the first one should be describing input of the filter. Please remember of ‘.filter:’ part. It will make sure that this one will appear in filters section.

HTML Views

Angular allows HTML files to have variables and simple logic evaluated within the markup.

A controller that has the same name will be the reference to vm, if the controller is different, don’t call it vm

General Conventions

  • If there is logic that is more complicated than a single if statement, move that logic to a controller
  • Use filters to format variable output — don’t format variables in a controller

Memory Leaks

This one is a bit tricky. It’s fairly hard to create a memory leak in AngularJS unless you’re mixing it with other external libraries that are not based on AngularJS(especially jQuery). Still, there are some things you need to remember while working with it, this article provides some general insight on how to find, fix and avoid memory leaks, for more detailed info I would suggest reading this article(it’s awesome!).

Finding memory leaks

I won’t lie, finding out if your application has some memory leaks is annoying, and localizing those leaks is even more annoying and can take a lot of time. Google Chrome devtools is incredible tool for doing this. All you need to do is:

  1. open you application
  2. go to the section you want to check for memory leaks
  3. execute the workflow you want to check for memory leaks so any service or cached data won’t be shown on the heap snapshot
  4. open devtools
  5. go to the Profiles tab
  6. select Take Heap Snapshot
  7. take a snapshot
  8. execute the workflow
  9. take a snapshot again
  10. go to a different state
  11. take a snapshot again
  12. select the last snapshot
  13. now click on the All objects select and choose Objects allocated between Snapshot 1 and Snapshot 2

This will show you the list of all objects, elements and so on, that were created during the workflow and are still residing in the memory. That was the easy part. Now we need to analyze the data we have and this might be quite tricky. We can click on object to see what dependency is retaining them. There is some color coding here that can be useful to you - red for detached elements and yellow for actual code references which you can inspect and see. It takes some time and experience to understand what’s going here but it gets easier and easier as you go.


Here are some anti-pattern that you should avoid and how to fix them.

Event handlers using scope

Let’s look at the following example. We have a simple directive that binds an on click action to the element.

(function() {

    'use strict';

        .directive('someDirective', someDirective);

    function someDirective() {
        var directive = {
            link: link
        return directive;

        function link(scope, element) {

            element.on('click', onClick);

            function onClick() {
                scope.someFlag = true;


The problem with this link function is that we’ve created a closure with context which retains the context, the scope and “then basically everything in the universe” until we unregister the handler from the element. That’s right, even after the element is removed from the DOM it will still reside in the memory retained by the closure unless unregister the handler. To do this we need to add a handler for ‘$destroy’ event to the scope object and then unregister the handler from the element. Here’s an example how to do it.

(function() {

    'use strict';

        .directive('someDirective', someDirective);

    function someDirective() {
        var directive = {
            link: link
        return directive;

        function link(scope, element) {

            element.on('click', onClick);

            scope.$on('$destroy', function() {

                //this will unregister the this single handler
      'click', onClick);

                //this will unregister all the handlers

            function onClick() {
                scope.someFlag = true;


Improper use of the $rootScope.$watch method

$rootScope.$watch can be a powerful tool, but it also requires some experience to use right. It allows the developers to create watchers that live through the whole application life and are only removed when they are explicitly said to unregister or when the application is closed, which may result in a huge memory leaks. Here are some tips on how to use them.

  • Use $scope.$watch when possible! If you’re using a watcher in a directive, it will have access to the scope object, add the watcher to it! This way we take advantage of AngularJS automatic watcher unregistration when the scope is deleted.

  • Avoid using $rootScope.$watch in factories. Don’t use it in factories unless you’re completely sure what you’re doing. Remember to unregister it when it is no longer needed! This takes us to the next bullet point.

  • Use them in Services. Watching for current locale can be great example of that. We’re using it with service, which is a singleton - it is only created once during application lifetime - and we want to watch for the current locale all the time we rather won’t want to stop at any point.

  • Unregister it if it is no longer needed. If you’re sure you won’t be needing that watcher any longer simply unregister it! Here’s an example

    var unregisterWatcher = $rootScope.$watch('someVariable', someMethod);

Using callback functions

Using callback isn’t the safest idea either as it can cause some function retention. AngularJS gives us awesome tool to bypass that - promises. They basically gives us the same behavior and are retention-risk free!