I'm trying to create a Visual Studio Code project from an existing website and I can't get IntelliSense to work properly. This is a pure HTML5/JavaScript ES5 website. I want to use VSCode to edit and debug under Chrome browser. This is our existing directory structure:

web/
   Product1/
      index.html
      main.js
      ui.js
   Product2/
      index.html
      main.js
      ui.js
   lang/
      lang_en.js
      (other language files)
   lib/
      (third party js files)
   shared/
      shared1.js
      shared2.js
      (other shared js files)

We use a javascript compiler to render each product to an index.html.gz file and embed that file into our products to be served by our internal web server.

I installed VSCode and created a workspace file in web/. I also created jsconfig.json in web/Product1/. This is the content of the jsconfig.json:

{
    "compilerOptions": {
        "module": "commonjs",
        "target": "es6"
    },
    "include": [
        "../images/*",
        "../lang/*",
        "../lib/*",
        "../shared/*"
    ]
}

I open shared1.js in the editor and right-click on an object that is defined in shared2.js and select "Go to definition", I get "No definition found for 'object'". If I open shared2.js and hover over the object definition, I get a brief "(loading...)" message. Once I do that, VSCode "Go to definition" will work between those files. If I exit VSCode and reopen the workspace, it can't find the object until I repeat this sequence. There are a lot of Google references to this problem but most give fixes that involve Node.js or Typescript. Nothing seems to work.

How do I get this to work every time?