You need to use the event.target which is the element which originally triggered the event. The this in your example code refers to document.
In jQuery, that's...
$(document).click(function(event) {
var text = $(event.target).text();
});
Without jQuery...
document.addEventListener('click', function(e) {
e = e || window.event;
var target = e.target || e.srcElement,
text = target.textContent || target.innerText;
}, false);
Also, ensure if you need to support < IE9 that you use attachEvent() instead of addEventListener().