test_1_25_2017_14_48

HTML

<p>
  Clicks: <span id="output">0</span>
</p>
<button id="click-btn">
  Count Clicks!
</button>

JavaScript

var output = document.getElementById("output");
var clickBtn = document.getElementById("click-btn");
//var clickArray = [0];
var x = 0;
clickBtn.onclick = function() {
  x += 1;
  i = 0;
  var nextOutput = output.innerHTML + ",";
  nextOutput += x;
  output.innerHTML = nextOutput;
};