JavaScript: How to find out which functions are called on event?

I have a problem, there is a website with a load of JS code. When I click on a certain element, some functions are called. How can I find out which functions (and in which files)?

For example, there's something like this

$( document ).ready(function() {
   $("a").on('click', function() { $('c').css('opacity', '0.8'); });
   $("ul#main li a").on('click', function() { $('c').toggle('.menu'); });
   $("nav a").on('click', function() { callSomeFunctions(); });
});

And then I've got a menu like this

click

How can I find out that those 3 lines above are executed?

Thanks!

Answer

I always use this tool to see what events are linked to DOM elements http://www.sprymedia.co.uk/article/visual+event