Explore enabling type acquisition for web TS Server

Follow up on #39707

Overview

We now have TSServer running in web environments, but it is currently limited to single file intellisense. It would be nice if we could also offer some IntelliSense for third party packages that are imported in the current file.

If a user is trying out react for example, we should be able to offer IntelliSense for React and ReactDOM:

//@ts-check

import * as React from 'react';
import * as ReactDOM from 'react-dom';

class HelloMessage extends React.Component {
    render() {
        return (
            <div>
                Hello {this.props.name}
            </div>
        );
    }
}

ReactDOM.render(
    <HelloMessage name="Taylor" />,
    document.getElementById('hello-example')
);

[orta]

I recently re-wrote the ATA for the Playground ( https://github.com/microsoft/TypeScript-Website/pull/1997 ) in what I think is a pretty good conceptual pattern:

• TypeScript can probably already give you a list of dependencies it knows about from the package.json, and the source files it has read (in the playground I don’t have this, so I use ts.preprocessFile to extract that)
• You make an API call which gets a list of all the files in each module tarball (I used jsDelivr’s) from which you can figure out the list of .d.ts files you need to download, or that you need to check DT.
• If you need to check for @types/module and grab the .d.ts files for that module
• Loop through all the downloaded .d.ts files and recurse grabbing their modules etc

It’s not exactly like that in practice (you need the version number before you can make that API call to jsdelivr) - but that’s good enough and you can read the implementation linked above for more details. The implementation of the TypeScript Playground ATA is built for third parties, so you could be a consumer of @typescript/ata when that PR lands.

An ideal state for VS Code which would keep this entirely first-party, is that the npm registry adds two APIs like:

• https://registry.npmjs.org/npm/:version_or_tag/contents which returns some sort of file list
• https://registry.npmjs.org/npm/:version_or_tag/file/package.json which returns a CDN’d file from the tarball (in this case the package.json)

Or vscode creates an API which proxies these APIs to jsdelivr (they’re real nice folks, I can make an intro if needed) which allows for other implementations behind the scenes in time.

[MartinKolarik]

Or vscode creates an API which proxies these APIs to jsdelivr (they’re real nice folks, I can make an intro if needed)

We are already watching - ping me any time if needed 😄