querystring: use String.prototype.split's limit

There's no need to add extra logic for it, `String.prototype.split` already has a `limit` argument. By using this argument we avoid keeping the whole array in memory, and V8 doesn't have to process the entire string. PR-URL: #2288 Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com> Reviewed-By: Michaël Zasso <mic.besace@gmail.com>

Author: Manuel Valls

lib/querystring.js

@@ -209,19 +209,20 @@ QueryString.parse = QueryString.decode = function(qs, sep, eq, options) {
  return obj;
  }
 
- qs = qs.split(sep);
-
  var maxKeys = 1000;
  if (options && typeof options.maxKeys === 'number') {
  maxKeys = options.maxKeys;
  }
 
- var len = qs.length;
  // maxKeys <= 0 means that we should not limit keys count
- if (maxKeys > 0 && len > maxKeys) {
- len = maxKeys;
+ if (maxKeys > 0) {
+ qs = qs.split(sep, maxKeys);
+ } else {
+ qs = qs.split(sep);
  }
 
+ var len = qs.length;
+
  var decode = QueryString.unescape;
  if (options && typeof options.decodeURIComponent === 'function') {
  decode = options.decodeURIComponent;