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EmberJS Component Class Bindings - 24 Mar 2016


Here’s a quick post on using one of ember’s lesser known component features. While recently working on the game of life in ember, I was able to create a cell component without a template.

This was accomplished by using classNameBindings, and a click event handler.

  import Ember from 'ember';
  const { get, set, computed } = Ember;
  const { alias } = computed;

  export default Ember.Component.extend({
    tagName: 'span',
    classNames: ['cell'],
    classNameBindings: ['alive'],
    alive: alias('cell.alive'),

    click() {
      set(this, 'alive', !get(this, 'alive'));
    }
  });

In this example, we’re using a simple version of classNameBindings where we’re just passing in a property. When the alive property returns true, the alive class is added. When that value is false, the cell component only has the default cell class.

Another way we could have handled this using classNameBindings would be passing in classes for both states.

  classNameBindings: ['alive:enabled:disabled']

In this example, we would add the enabled class for a truth value, and the disabled class for a false value.