Code Style


What we’re aiming for:

<!doctype html>
<html lang="en-gb">
<!-- Head -->
  <h1 class="alpha" id="myTitle">Title</h1>
  <div class="foo" id="bar" data-baz="foobar" role="banner" aria-labelledby="myTitle">
    <p>Lorem ipsum dolor mit...</p>
<!-- Stuff -->



Using the HTML5 doctype helps ensure that documents are rendered in standards mode1 across all browsers.

<!doctype html>

Language Attribute

Ensure that the language attribute is set on your document: it’s one of the low-hanging fruit for helping assisitive technologies.

<html lang="en-gb">

Authors are encouraged to specify a lang attribute on the root html element, giving the document’s language. This aids speech synthesis tools to determine what pronunciations to use, translation tools to determine what rules to use, and so forth.

Attribute Order

As classes see the most activity and are the most useful attribute, they are authored first. The ID attribute should be reserved for anchors, JavaScript, and accessibility hooks.

Boolean attributes

Using HTML5 means that there is no need for a declared value on attributes such as disabled, hidden, and checked. The W3C and WhatWG2 both declare that:

The presence of a boolean attribute on an element represents the true value, and the absence of the attribute represents the false value.

<input type="text" disabled>



We use CSScomb3 and the appropriate configuration file4, to enforce a “house” style:

Declaration Order

Declarations are grouped as per the example below:

.foobar {
  // Positioning
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;

  // Box-model
  display: block;
  margin: auto;
  padding: 1em;
  height: 100px;
  width: 100%;

  // Typography
  font-size: 1.2em;
  line-height: 1.1;
  color: #333;
  text-align: center;

  // Visual
  background-color: #017d87;
  border-bottom: 1px solid #ebebeb;

  // Misc
  table-layout: fixed;

Those declarations that control the positioning of an element within the document are raised to the top of the ruleset: they have the most impact on how the browser’s layout engine applies the box model.

Media Queries

Group media queries with the selector that they relate to, rather than placed at the end of the stylesheet or in a separate document altogether. While there’s an argument that repeating the @media (min-width: 480px) { ... } declaration breaks the principle of DRY and increases file-size, the benefits of seeing the media query in context outweight the negatives - particularly when gzip and minification tools are available.

Breakpoint Definitions

When using a pre-processor, breakpoint values should be declared in a single place alongside the rest of the stylesheet variables.

Media Query Splitting

Where applicable, take advantage of media-query splitting5 in an effort to avoid introducing styles, only to have to overwrite them later.

@media (max-width: 479px) {
  // Small
@media (min-width: 480px) and (max-width: 719px) {
  // Medium
@media (min-width: 720px) and (max-width: 1199px) {
  // Large



A comprehensive list of JavaScript style guide lines6 can be found on Airbnb webpage. An ESLint7 configuration known as eslint-config-airbnb8 has been implemented based on the style guide lines to help developers when working within an IDE. These are the standards which our code should adhere to.

The following configuration should be place either locally to the project or globally at ~/.eslintrc. The env and extends value should be adjusted to cater for the project’s needs.

    "env": {
        "browser": true,
        "node": true,
        "mocha": true,
        "mongo": true
    "extends": "airbnb/legacy"

Pre-commit hooks

A pre-hook should be appended to the project to fail the commit if the user is attempting to submit new or modified code which doesn’t pass the linter. This will allow a pre-exisitng project to evolve over time & new projects to stay lint free from the start.

Any potential broken windows that are related to a linting rule should be fixed, but a big bang approach in fixing all violations should be avoided to prevent large code churn.

New Projects

When a new project is created it should comply with the approaches above from day one.