Code style

React components

When writing React components, try to follow the following guidelines:

  • Keep components small. If a component gets too big, it might be worth splitting it out into smaller pieces.
  • Keep state to a minimum. A component without anything in state and only props would be best. When state is needed, make sure nothing is redundant and can be derived from other state values. Move state upstream (to parent components) as much as it makes sense.
  • Use the propTypes attribute to document what props the component requires; use isRequired as the default unless the prop is truly optional.

More on state:

  • Each page (app/pages is a connected "smart" component (in redux's terminology) that is connected to our redux store, which holds and manages all global app state.
  • Each page (app/pages) can hold some state specific to that page.
  • Reusable components (app/components) typically hold no state (with rare exceptions, like forms).

Please also review:

And when writing new components, try to follow the ES6 and React standards we are now using in the viz repo.


Prefix all CSS classes with the component name. For example, if I'm working on the PatientList component, I'll prefix CSS classes with patient-list-.

Keep styles in the same folder as the component, and import them in the main app/style.less stylesheet. If working on a "core" style, don't forget to import the files in app/core/core.less.

In organizing the core styles in different .less files, as well as naming core style classes, we more or less take inspiration from Twitter Bootstrap (see

Some styles we'd rather not use on touch screens (for example hover effects which can be annoying while scrolling on touch screens). For that purpose, a small snippet (app/core/notouch.js) will add the .no-touch class to the root document element, so you can use:

.no-touch .list-item:hover {
  // This will not be used on touch screens
  background-color: #ccc;


We use an icon font for app icons (in app/core/fonts/). To use an icon, simply add the correct class to an element (convention is to use the <i> element), for example:

<i class="icon-logout"></i>

Take a look at the app/core/less/icons.less file for available icons.


In a separate terminal, you can lint JS files with:

$ npm run lint