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: #1385 Reviewed-By: Ben Noordhuis <[email protected]>
nodejs · Apr 10, 2015 · f0bf6bb · f0bf6bb
1 parent 8bc8bd4
commit f0bf6bb
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diff --git 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;

diff --git a/test/parallel/test-readline-interface.js b/test/parallel/test-readline-interface.js
@@ -216,6 +216,18 @@ function isWarned(emitter) {
     fi.emit('data', ''); // removes listener
   });
 
+  // calling readline without `new`
+  fi = new FakeInput();
+  rli = readline.Interface({ input: fi, output: fi, terminal: terminal });
+  called = false;
+  rli.on('line', function(line) {
+    called = true;
+    assert.equal(line, 'asdf');
+  });
+  fi.emit('data', 'asdf\n');
+  assert.ok(called);
+  rli.close();
+
   if (terminal) {
     // question
     fi = new FakeInput();