Edit in JSFiddle

var notDebouncedCount = 0;
var debouncedCount = 0;

var notDebouncedElem = document.getElementById('not-debounced');
var debouncedElem = document.getElementById('debounced');

var notDebouncedFunc = function() {
	notDebouncedElem.innerHTML = ++notDebouncedCount;
};

var debouncedFunc = _.debounce(function() {
	debouncedElem.innerHTML = ++debouncedCount;
}, 100);


document.documentElement.onmousemove = function() {
	notDebouncedFunc();
  debouncedFunc();
};