Add "TypeChat in 5 Minutes" doc

[DanielRosenwasser]

I'm not sure if this is the appropriate title - but I think this sort of doc would be helpful for users who are looking for a breakdown of our sentiment example.

Some TODOs:

• Add the "here's how it looks when put together"
• Make sure it all can be copy-pasted together
• Decide on the right title if not this

[pierceboggan]

What does "mostly" mean here?

[pierceboggan]

It might be worth being explicit that your schema can (obviously) contain multiple types, but you must specify the "entry" type.

[weykon]

Looking forward to this PR

[bennycode]

Thank you @DanielRosenwasser for offering this handy guide on using TypeChat. I was very excited when I first learnt about TypeChat and quickly went through the examples to integrate it with my existing code.

During the process, I encountered some challenges when using TypeChat within an ESM module. I'd like to share my findings, as they might be helpful in preventing difficulties for others.

I tried to load the schema file but noticed that you cannot simply target it with __dirname:

// Load up the schema file contents.
const schema = fs.readFileSync(path.join(__dirname, "sentimentSchema.ts"), "utf8");

After executing the code, I got the following error:

ReferenceError: __dirname is not defined in ES module scope

I was able to solve this problem by mimicking the behavior of __dirname and __filename using import.meta:

import fs from 'node:fs';
import path from 'node:path';
import {fileURLToPath} from 'node:url';

const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);

const texts = path.join(__dirname, 'texts.txt');
const schemaFile = path.join(__dirname, 'sentimentSchema.ts');

// Load up the schema file contents.
const schema = fs.readFileSync(schemaFile, 'utf8');

I encountered another issue when trying to import the schema using the following method:

// Load up the type from our schema.
import type { SentimentResponse } from "./sentimentSchema";

I received a CustomError because Node.js couldn't locate the module, even though I was running my code using ts-node-esm:

CustomError: Cannot find module

After doing some research, I found that file extensions are mandatory when using ES Modules to resolve relative specifiers. Since .ts extensions are only supported with allowImportingTsExtensions, I made the decision to use .js extensions (even though I was referring to TS code), and it did the trick for me:

// Load up the type from our schema.
import type { SentimentResponse } from "./sentimentSchema.js";

The rest of the description worked perfectly, and I'm very happy about what you and the team are creating here. I'm so happy that I even created a TypeChat video tutorial, and it's not longer than 5 minutes. So, "TypeChat in 5 Minutes" is a reality! 😊

Great job! 👍

Sending my best wishes from Berlin!
Benny

[DanielRosenwasser]

Thanks @bennycode, this is great feedback - I hadn't yet gotten the chance to work on ESM examples, and I knew that there would be some rough patches with __dirname. It'd be ideal for all of our example code to just work across ESM and CJS, but import.meta isn't available outside of modules.

[hjonasson]

I read through the entire doc and learned a lot! Can/will this PR be completed?