until(fn:Function, delay:Number):Function

until.js

/**
 * Returns a function which won't be invoked until delay has elapsed, without further calls being made during that interval.
 * If further calls are made, the delay is reset and the cycle repeats.
 * @param  {Function} fn     Behaviour to be wrapped in this delay
 * @param  {Number}   delay  Duration in milliseconds
 * @return {Function}
 */
function until(fn, delay) {
  var timeoutId;
  var scheduledCall = setTimeout.bind(window, fn, delay);

  return function() {
    clearTimeout(timeoutId);
    timeoutId = scheduledCall.apply(this, arguments);
  };
}

Example

var snarfLater = until(function () {
  console.log('snarf!');
}, 2000);

snarfLater();
snarfLater();
snarfLater();
snarfLater();

... 2 seconds pass

>> "snarf!"