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Add loader supporting mixed-format packages #8

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Merged
JakobJingleheimer merged 3 commits into from
Aug 31, 2022
Merged

Add loader supporting mixed-format packages #8

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119ddf1
Add loader to support mixed-format packages
JakobJingleheimer Aug 25, 2022
ec656c6
add nested cjs via require
JakobJingleheimer Aug 25, 2022
86ef7ce
Update mixed-format/loader.mjs
JakobJingleheimer Aug 31, 2022
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1 change: 1 addition & 0 deletions mixed-format/fixture/cjs.js
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exports.qux = require('./cjs2.js');
1 change: 1 addition & 0 deletions mixed-format/fixture/cjs2.js
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module.exports = 'zed';
1 change: 1 addition & 0 deletions mixed-format/fixture/esm.js
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export const foo = 'bar';
3 changes: 3 additions & 0 deletions mixed-format/fixture/package.json
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{
"type": "commonjs"
}
34 changes: 34 additions & 0 deletions mixed-format/loader.mjs
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export async function load(url, context, nextLoad) {
if (!url.endsWith('.js')) return nextLoad(url);

const nextResult = await nextLoad(url, { ...context, format: 'module' })
.then((result) => {
if (containsCJS(result.source)) { throw new Error('CommonJS'); }

return result;
})
.catch(async (err) => {
if (
(err?.message.includes('require') && err.includes('import'))
|| err?.message.includes('CommonJS')
) {
return { format: 'commonjs' };
}

throw err;
});

return nextResult;
}

function containsCJS(source) {
const src = '' + source;

// A realistic version of this loader would use a parser like Acorn to check for actual `module.exports` syntax
if (src.match(/exports[\.( ?=)]/)) { return true };

if (
src.match(/require\(/)
&& !src.match(/createRequire\(/)
) return true;
Comment on lines +28 to +33
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@aduh95 aduh95 Aug 31, 2022

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We should be using /regex/.test here, much faster than 'string'.match as it doesn't need to create an array.

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@JakobJingleheimer JakobJingleheimer Aug 31, 2022

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Ahh, good call. I'll send an update this evening

}
8 changes: 8 additions & 0 deletions mixed-format/test.mjs
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import assert from 'node:assert';

import { foo } from './fixture/esm.js';
import { qux } from './fixture/cjs.js';


assert.strictEqual(foo, 'bar');
assert.strictEqual(qux, 'zed');