Fixes #358: add better JSdocs. Fixes issue with match method & enhances path method

Author: webketje

lib/helpers.js

@@ -16,6 +16,9 @@ function isObject(o) {
 function isString(s) {
   return typeof s === 'string'
 }
+function isUndefined(u) {
+  return typeof u === 'undefined'
+}
 
 /**
  * Recursively remove a directory
@@ -52,6 +55,7 @@ const helpers = {
   isNumber,
   isString,
   isObject,
+  isUndefined,
   rm
 }