example.js

// Observe click events on h1 elements
$('h1').on('click', function( event ) {
  // This is the body of the click handler.
  // Notice we were passed the click event as a parameter.
  
  // From in here, we can access event to get info about it.
  var h1 = event.currentTarget;
  
  // Interestingly, "this" also refers to the item that was clicked
  h1 == this; // would evaluate to true
  
  // But h1 is just a bare DOM object. If we wanted to call
  // jQuery methods on it, we need to extend it.
  
  // We can do that inline...
  $(h1).siblings('a').hide();
  
  // Or we can store the extended element in a variable so we
  // don't need to keep calling $() to extend it...
  var $h1 = $(h1);
  
  $h1.siblings('a').hide();
  $h1.css({color: 'blue'});
});