Let"s not dwell on the concept of anti-shaking and throttling, but let"s ask what"s the difference between the two. The first is the implementation of underscore

 _.now = function (){return new Date().getTime()};
_.debounce = function(func, wait, immediate){
    var timeout, args, context, timestamp, result; 
    var later = function(){
        var last = _.now() - timestamp; 
        if (last < wait && last >= 0) { 
            timeout = setTimeout(later, wait - last); // 
        }else{
            timeout = null;
            result = func.apply(context, args);
            if (!timeout) context = args = null;
        }
    };
    return function(){ 
      context = this; 
      args = arguments; 
      timestamp = _.now(); 
      if (!timeout) 
         timeout = setTimeout(later, wait);
      return result;
    };
};

split

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

what"s the difference between the above two?