readline: fix calling constructor without new

Previously, we detected options object based on amount of arguments
supplied. But if we're calling readline without new operator,
constructor gets re-called and will always have 4 arguments.

PR-URL: https://github.com/iojs/io.js/pull/1385
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

1 files changed, 4 insertions, 1 deletions

diff --git a/lib/readline.js b/lib/readline.js
index 63a7aa816..a6845010d 100644
--- a/lib/readline.js
+++ b/lib/readline.js
@@ -26,7 +26,10 @@ exports.createInterface = function(input, output, completer, terminal) {
 
 function Interface(input, output, completer, terminal) {
   if (!(this instanceof Interface)) {
-    return new Interface(input, output, completer, terminal);
+    // call the constructor preserving original number of arguments
+    const self = Object.create(Interface.prototype);
+    Interface.apply(self, arguments);
+    return self;
   }
 
   this._sawReturn = false;