Verbatim copy of underscore.js' debounce function, as a jquery plugin (amd friendly)

jquery.debounce.js

;(function (factory) {
    if (typeof define === 'function' && define.amd) {
        define(['jquery'], factory);
    } else {
        factory(jQuery);
    }
}(function ($) {

  // Thefted from Underscore.js 1.8.3
  // (c) 2009-2015 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors

  // Docs: http://underscorejs.org/#debounce

  // Returns a function, that, as long as it continues to be invoked, will not
  // be triggered. The function will be called after it stops being called for
  // N milliseconds. If `immediate` is passed, trigger the function on the
  // leading edge, instead of the trailing.
  $.fn.debounce = function(func, wait, immediate) {
      var timeout, args, context, timestamp, result, _ = {};

      _.now = Date.now || function() {
        return new Date().getTime();
      };

      var later = function() {
        var last = _.now() - timestamp;

        if (last < wait && last >= 0) {
          timeout = setTimeout(later, wait - last);
        } else {
          timeout = null;
          if (!immediate) {
            result = func.apply(context, args);
            if (!timeout) context = args = null;
          }
        }
      };

      return function() {
        context = this;
        args = arguments;
        timestamp = _.now();
        var callNow = immediate && !timeout;
        if (!timeout) timeout = setTimeout(later, wait);
        if (callNow) {
          result = func.apply(context, args);
          context = args = null;
        }

        return result;
      };
    };

}));