VS Code Intellisense seems to wrongly infer revealing module pattern

From @lodybo on September 12, 2017 9:44

• VSCode Version: 1.16.0
• OS Version: Windows 10

Steps to Reproduce:

1. Copy the code below into a file called greeter.js
2. Run node greeter.js in a terminal

var Greeter = (function(country) {
  // Private
  this.country = country;

  function getCountry() {
    return country;
  }
  
  // Public
  var performGreeting = function (name) {
    var country = getCountry();
    
    return 'Hello ' + name + ', from ' + country;
  }
  
  return {
    greet: performGreeting
  }
});

var greeter = new Greeter("The Netherlands");
console.log(greeter.greet("Lody"));
console.log(greeter.country);

Using the revelealing module pattern in VS Code seems to trip up Intellisense into suggesting the wrong members. The code above was tested in multiple browsers and consoles and run with Node v6.3.0 which behaved as expected. They ran the greet() function and returned undefined for greeter.country:

λ node greeter.js
Hello Lody, from The Netherlands
undefined

But VS Code's Intellisense reports that greeter only contains country:

It also reports the expected interface of greeter for the class itself (Greeter):

What is expected is VS Code correctly inferring greeter.greet to be a function of Greeter, with a parameter name.

This was reproduced in a clean folder of VS Code, with no extensions (launched with code --disable-extensions), and no jsconfig.json.

Copied from original issue: Microsoft/vscode#34214

まず、VS Code IntelliSense で提供されている greeter.js の例を使って問題を再現し、推論されたメンバーを Node.js の出力と比較します。IntelliSense が greeter.greet を name を受け取る関数として識別し、country をパブリックメンバーとして公開しなければ、作業は完了です。