Simple counter

index.html

<style>
  #counter {
    width:100%;
    height:100%;
    font-size:400px;
    text-align:center;
    padding-top:40px;
    overflow:hidden;
  }
  ::selection {
    background: transparent;
  }
  body {
    overflow:hidden;
  }
</style>
<div id="counter">0</div>
<script src="http://d3js.org/d3.v3.min.js" charset="utf-8"></script>
<script>
  var counter = d3.select("#counter")
  counter.on("click", count);
  var val = 0;
  function count() {
    val++
    counter.text(val);
  }
</script>