Package data for NPM as ESM and CJS

[lucacasonato]

Previously only a CJS entrypoint was provided. This provides a ESM
entrypoint that can be directly used from Deno or a browser.

[queengooborg]

Thank you for splitting this out, I'm super excited for this! 😄 I have just a small suggestion and a question, but from a quick skim of the code this is looking good to me overall!

[queengooborg]

Okay, so I had a feeling this might be a breaking change, and it looks like my suspicions were correct. BCD's exported packages don't expose the version number, so I require the included package.json and use that instead. By adding the exports key to the package.json, I wouldn't be able to require any file I wanted from the package, so my program would break. We should be sure to bump the major semver when this is launched!

[lucacasonato]

Import assertions are now widely available in server side runtimes. Chrome supports them, and so do both Deno (since 1.17) and Node (since v17). As such we could now keep the JSON in a seperate file for publishing again, and then re-export it from the ESM module using import assertions.

@queengooborg We could do the same with the version from package.json.

[lucacasonato]

Actually - scrap that. Node 17 does not support JSON modules without the --experimental-json-modules flag... :/

I guess the current thing here is the best thing we could do for now.

[lucacasonato]

Node unflagged import assertions in v17.5.0 (released 2022-02-10). Probably too soon to rely on them?

[queengooborg]

Yeah, I'd say it's too soon, especially since our developer requirement is NodeJS v14. Thanks for double-checking!

[lucacasonato]

Makes sense. Once the requirement is NodeJS v18, this is the patch to apply to clean up:

From: Luca Casonato <[email protected]>
Date: Thu, 7 Apr 2022 23:29:06 +0200
Subject: [PATCH] Use import assertions to import data in ESM

---
 scripts/release-build.js | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/scripts/release-build.js b/scripts/release-build.js
index eaba25e7e..fd2a20a9c 100644
--- a/scripts/release-build.js
+++ b/scripts/release-build.js
@@ -20,9 +20,9 @@ async function writeData(data) {
   await fs.writeFile(dest, data);
 }
 
-async function writeIndexESM(data) {
+async function writeIndexESM() {
   const dest = path.resolve(directory, 'index.js');
-  const content = `export default ${data};\n`;
+  const content = `import data from "./data.json" assert { type: "json" };\nexport default data;\n`;
   await fs.writeFile(dest, content);
 }
 
@@ -91,7 +91,7 @@ async function main() {
 
   await writeManifest();
   await writeData(data);
-  await writeIndexESM(data);
+  await writeIndexESM();
   await copyFiles();
 
   console.log('Data bundle is ready');
-- 
2.35.1

[queengooborg]

I went ahead and updated the readme to include an ESM import example, but all in all this is looking great to me! Thank you so much for this, I'm super excited to see this in the next release!