A JavaScript throttling function.

throttle.js

module.exports = function(callback, threshold) {
  var isReady = true;
  var onceMore = false;
  var context;
  var args;
  function trigger() {
    isReady = false;
    callback.apply(context, args);
    setTimeout(refresh, threshold); 
  }
  function refresh() {
    isReady = true;
    if (onceMore) {
      trigger();
    }
  }
  return function() {
    context = this;
    args = arguments;
    if (isReady) {
      trigger();
    } else {
      onceMore = true;
    }
  };
};