how to make clickable element in html and onclick event code example

Example 1: javascript onclick

var myElem = document.getElementByID('ElemID');
myElem.onclick = function() {
	//do stuff
}

Example 2: button click function in js

<script>
  $(document).ready(function(){
    $('#MyButton').click(function(){
       CapacityChart();
    });
  });
</script>

<input type="button" value="Capacity Chart" id="MyButton" >