mlhToggle.js

var s = '<button id="pastToggle" style="margin: 0 auto;display:block;">Show/Hide Past Hackathons</button>'; // HTML string

var div = document.createElement('div');
div.innerHTML = s;
$('.row.feature').children().get(0).append(div);

$('#pastToggle').click(function() {
  $('.event').each(function(item){
	var date = Date.parse($(this).find('meta[itemprop="endDate"]').attr('content'));
	var currentTime = (new Date).getTime();
	var inPast = date<currentTime;
	if(inPast){
    	console.log($(this).toggle());
	}
	});
});