How do I use variables in canJS?

Here is the code I am trying to play around with. In my JS file I have: $count = 0

In my HTML I am trying:

{{#if categories}}
<div id="categories">
  {{#each categories}}
  {{count = count + 1}}
  <div class="category" url="{{url}}">
    <div class="category-icon"></div>
    <div class="category-name">{{name}}</div>
    <span class="category-info"></span>
  </div>
  {{#if !(count%3)}}
		<br/>
	{{/if}}
  {{/each}}
</div>
{{/if}}

I want there to be a new line after every three categories I display - is there a way to do this with canJS?

You can add a simple helper everyThird and use @index helper provided with stache engine. Demo.

helpers: {
    everyThird: function(val) {
        return val && val%3 === 0;
    }
}

inside template

  <ul>
  {{#each categories}}
    {{#if everyThird(@index)}}
     <li><hr></li>
    {{/if}}
    <li>{{name}}</li>    
  {{/each}}
  </ul>