• Use 4 space indentation and not tabs
  • Use camelCase for variables and not underscores or dashes
  • Use dot annotation . for javascript file naming
  • Use single-quotes ' for all values
  • Use a maximum length of 120 characters, however 80 is preferred
  • Use base.js for global and general functions and avoid adding js files to the root
  • Use the frameworks prefix inside the addons folder
  • Use the module and singleton pattern to structure code
  • Use the js- prefix when working with JS related selectors and do not add stylings to it
  • JavaScript should validate JS Lint
  • Use full words instead of shorthands like number instead of nr
  • Keep <script> and the following starting enclosure on the same level
  • Separate all script tags within a {% addtoblock "js" %}
  • Do not use inline JS within HTML attributes such as onclick="" or onload=""
  • Do not use inline JS within HTML, try to implement JavaScript files only
  • Do not add spaces when writing if (true) {} else {} or function helloWorld() {}
  • Always use semicolons and full brackets except shortcuts like var i = (true) ? 'yes' : 'no'; or single lines if (index <= 0) index = 0;
  • Always declare variables on top of the functions and not in-between
  • Never use $ for variable names like var $el = $('.el');
  • Never use comma separation for variable declerations like var a, b, c;
  • Ensure that JavaScript widgets don’t create disturbances while the DOM is loading
  • Please make sure that & has a character reference like “&amp;”

Additionally follow the “Code Conventions for the JavaScript Programming Language”:


jQuery(document).ready(function () {

    var Cl.MyApp = {
        load: function {
            alert('hello world');

    // load application



When using jQuery to refer to a DOM instance, always use the js- prefix to separate styles from JavaScript functionality. For example: <div class="addon addon-gallery js-addon-gallery"></div>.

In this example, addon and addon-gallery define styles according to BEM principles and js-plugin-gallery refers to the JavaScript functionality attached to the DOM element.

Even when removing the js class (or just waiting for javascript to kick in), the addon should still look ok.