JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://cdn.ractivejs.org/edge/ractive.js"></script>
<main></main>

<script id='template' type='text/ractive'>
    <div class="mains">
    {{ #files:i }}
    <button on-click='setIndex:0'>set to 0</button>
    <button on-click='setIndex:1'>set to 1</button>
    {{ >tab }}
    {{ /files }}
    </div>
    <!-- {{>tab}} -->
    <div>
        <span>{{ files[i].collection[activeIndex].name }}</span>
    </div>
    <!-- {{/tab}} -->
</script>

CSS

body {
    font-family: 'Helvetica Neue', arial, sans-serif;
    font-weight: 200;
    color: #353535;
}

h1, h2, h3, h4, h5, h6 {
    font-weight: 200;
}

JavaScript

var ractive = new Ractive({
    el: 'main',
    template: '#template',
    data: { files: [{
        project: 0,
        activeIndex: 1,
        collection: [
            { type: "coffee", name: "thisIsALongFileName.coffee", path: "" },
            { type: "js", output: true, name: "thisIsALongFileName.js", path: "js/"}
        ]
    }] }
});

ractive.on( 'setIndex', function ( event, index ) {
    this.set( event.keypath + '.activeIndex', index );
});