异步版本
\Asynchronous version
// coffeescript-hooks.mjs
import { readFile } from 'node:fs/promises';
import { findPackageJSON } from 'node:module';
import coffeescript from 'coffeescript';
const extensionsRegex = /\.(coffee|litcoffee|coffee\.md)$/;
export async function load(url, context, nextLoad) {
if (extensionsRegex.test(url)) {
// CoffeeScript files can be either CommonJS or ES modules. Use a custom format
// to tell Node.js not to detect its module type.
const { source: rawSource } = await nextLoad(url, { ...context, format: 'coffee' });
// This hook converts CoffeeScript source code into JavaScript source code
// for all imported CoffeeScript files.
const transformedSource = coffeescript.compile(rawSource.toString(), url);
// To determine how Node.js would interpret the transpilation result,
// search up the file system for the nearest parent package.json file
// and read its "type" field.
return {
format: await getPackageType(url),
shortCircuit: true,
source: transformedSource,
};
}
// Let Node.js handle all other URLs.
return nextLoad(url, context);
}
async function getPackageType(url) {
// `url` is only a file path during the first iteration when passed the
// resolved url from the load() hook
// an actual file path from load() will contain a file extension as it's
// required by the spec
// this simple truthy check for whether `url` contains a file extension will
// work for most projects but does not cover some edge-cases (such as
// extensionless files or a url ending in a trailing space)
const pJson = findPackageJSON(url);
return readFile(pJson, 'utf8')
.then(JSON.parse)
.then((json) => json?.type)
.catch(() => undefined);
}