[Demo] Use AI to codemod this repo to TS

[NickHeiner]

I did this by running the following command:

jscodemod --prompt "// Convert the code above to TypeScript. Be sure to retain any variables imported via require. Use ESM instead of CommonJS for imports and exports. Remove the \"use strict\" directive. You can import the following global types from `my-global-types` and use them as you see fit: `GameState`, `Player`, `MovePart`, `Row`, `Col`, `Space`." ../camelot-engine/lib/**/*.js

Using jscodemod's AI system, powered by OpenAI.

Comparison to previous tools

Before AI codemods, we could use something like https://github.com/airbnb/ts-migrate/. However, useful as that tool is, it's limited to very coarse-grained types – it basically just inserts any everywhere.

With an AI codemod, it's actually able to infer types from the surrounding usage:

function f(a, gameState, b) {
  console.log(a.c, gameState);
  a.c(b || 'default-value');
}

// ts-migrate result
function f(a: any, gameState: any, b: any) {
  console.log(a.c, gameState);
  a.c(b || 'default-value');
}

// AI result
import type { GameState } from 'my-global-types';
function f(a: { c: (arg: string) => void }, gameState: GameState, b?: string): void {
  console.log(a.c);
  a.c(b || 'default-value');
}

Additionally, to use ts-migrate on my large production codebase at Netflix, I had to make a bunch of changes over 4 days. By contrast, the only setup time for the AI-powered TypeScript conversion was 4 minutes of tweaking the prompt.