pluralize helper

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  numberOfPeople: 0,
  
  actions: {
    increment(delta=1) {
   		this.incrementProperty('numberOfPeople', delta);
    }
  }
});

templates.application.hbs

<button onclick={{action 'increment' 1}}>+</button>
<button onclick={{action 'increment' -1}}>-</button>

Found {{pluralize numberOfPeople "person"}}

twiddle.json

{
  "version": "0.13.0",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.16.2",
    "ember-template-compiler": "2.16.2",
    "ember-testing": "2.16.2"
  },
  "addons": {
    "ember-data": "2.16.3"
  }
}