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Sprinkling Little Bits of Behavior Using JavaScript Modules

Published June 14, 2016

We often encounter scenarios where we need a small piece of (somewhat) simple functionality on a single page. After a successful 15-minute yak-shave-code-off, we've figured out a solid way to tackle this requirement.


Initially, I wanted to prefix classes with .js- to illustrate that our Javascript had dependencies on those DOM elements. It quickly became evident that this was a mistake - it caused the duplication of class names (save the .js- prefix), and mixing that prefix with styling seemed dirty.


After our code-off, and in essence generating code that was 98% identical, we settled on having a JavaScript module class name at the top level, and keeping general, descriptive class names for styling and interaction at lower levels. This saves us duplicate class names, but still alerts other developers to the fact that JavaScript utilizes classes within. This also allows us to transition to React or Backbone and have JavaScript build the elements within our module container.

Below is an example of an activator module for adding/removing items from an "active" list. (Try it out here)



<div class="js-item-activator"> 
  <div class="item-list active"></div>
  <div class="item-list inactive">
    <div class="item">Item 1</div>
    <div class="item">Item 2</div>
    <div class="item">Item 3</div>



$(function() {
  var $module = $('.js-item-activator');
  $('body').on('click', '.active .item', function() {
    var $item = $(this);$item.detach().appendTo($module.find('.inactive'));

  $('body').on('click', '.inactive .item', function() {
    var $item = $(this);$item.detach().appendTo($module.find('.active'));


  background: #eee
  border: 1px solid #ddd
  margin-bottom: 10px
  min-height: 30px
  overflow: hidden
  padding: 10px

    background: #ddd
    border: 1px solid #ccc
    cursor: pointer
    float: left
    margin-right: 10px
    padding: 5px 10px
Author details

Mark Norman

(Former senior developer)