feat: add require exports & esm -> cjs conversion

Author: lukeed

deno.lock

@@ -12,23 +12,28 @@
 	"exports": {
 		"./access": {
 			"types": "./access.d.ts",
-			"default": "./access.mjs"
+			"import": "./access.mjs",
+			"require": "./access.js"
 		},
 		"./find": {
 			"types": "./find.d.ts",
-			"default": "./find.mjs"
+			"import": "./find.mjs",
+			"require": "./find.js"
 		},
 		"./package": {
 			"types": "./package.d.ts",
-			"default": "./package.mjs"
+			"import": "./package.mjs",
+			"require": "./package.js"
 		},
 		"./resolve": {
 			"types": "./resolve.d.ts",
-			"default": "./resolve.mjs"
+			"import": "./resolve.mjs",
+			"require": "./resolve.js"
 		},
 		"./walk": {
 			"types": "./walk.d.ts",
-			"default": "./walk.mjs"
+			"import": "./walk.mjs",
+			"require": "./walk.js"
 		},
 		"./package.json": "./package.json"
 	},

package.json

@@ -8,6 +8,7 @@ import { join, resolve } from 'node:path';
 
 import oxc from 'npm:[email protected]';
 import { minify } from 'npm:[email protected]';
+import * as CommonJS from './commonjs.ts';
 
 const Quiet = Deno.args.includes('--quiet');
 
@@ -59,6 +60,7 @@ async function transform(filename: string) {
 	}
 
 	let rgx = /\.tsx?$/;
+	let cjs = filename.replace(rgx, '.js');
 	let esm = filename.replace(rgx, '.mjs');
 	let dts = filename.replace(rgx, '.d.ts');
 
@@ -70,6 +72,12 @@ async function transform(filename: string) {
 	log('> writing "%s" file', esm);
 	await Deno.writeTextFile(outfile, xform.code);
 
+	// esm -> cjs
+	outfile = join(outdir, cjs);
+	log('> writing "%s" file', cjs);
+	let tmp = CommonJS.transform(xform.code);
+	await Deno.writeTextFile(outfile, tmp);
+
 	try {
 		let min = minify(esm, xform.code, {
 			mangle: { toplevel: true },

scripts/build.ts

@@ -0,0 +1,97 @@
+import MagicString from 'npm:[email protected]';
+import { type Function, parseSync } from 'npm:[email protected]';
+import { walk } from 'npm:[email protected]';
+
+type Location = {
+	start: number;
+	end: number;
+};
+
+export function transform(esm: string) {
+	let s = new MagicString(esm);
+	let ast = parseSync('file.js', esm).program;
+
+	walk(ast.body, {
+		ImportDeclaration(n) {
+			let { start, end } = n as unknown as Location;
+			let src = n.source as unknown as {
+				type: 'StringLiteral';
+				value: string;
+				start: number;
+				end: number;
+			};
+
+			let from = src.value;
+
+			// NOTE: remove "node:" for Node < 14
+			// https://nodejs.org/api/esm.html#node-imports
+			// if (from.startsWith('node:')) {
+			// 	from = from.substring(5);
+			// }
+
+			let $locals: string[] = [];
+			let $default: string | undefined;
+
+			let i = 0, arr = n.specifiers;
+			let tmp: typeof arr[number];
+
+			for (; i < arr.length; i++) {
+				tmp = arr[i];
+
+				switch (tmp.type) {
+					case 'ImportDefaultSpecifier':
+					case 'ImportNamespaceSpecifier': {
+						if ($default) throw new Error('Double `default` exports!');
+						$default = tmp.local.name;
+						break;
+					}
+
+					case 'ImportSpecifier': {
+						let { imported, local } = tmp;
+						if (imported.name !== local.name) {
+							$locals.push(`${imported.name}: ${local.name}`);
+						} else {
+							$locals.push(local.name);
+						}
+						break;
+					}
+				}
+			}
+
+			let stmt = 'const ';
+			if ($default) {
+				stmt += $default;
+			}
+			if ($locals.length > 0) {
+				if ($default) stmt += ', ';
+				stmt += '{ ' + $locals.join(', ') + ' }';
+			}
+
+			let qq = s.snip(src.start, src.start + 1);
+			stmt += ` = require(${qq + from + qq});`;
+			s.overwrite(start, end, stmt);
+		},
+		ExportDefaultDeclaration(n) {
+			let start = (n as unknown as Location).start;
+			s.overwrite(start, start + 'export default'.length, 'module.exports =');
+		},
+		ExportNamedDeclaration(n) {
+			let start = (n as unknown as Location).start;
+			let type = n.declaration?.type;
+			let key: string | undefined;
+
+			if (type === 'FunctionDeclaration') {
+				key = (n.declaration as Function).id?.name;
+			} else {
+				console.log('EXPORT NAMED TYPE?', n.declaration);
+			}
+
+			if (key) {
+				s.remove(start, start + 'export '.length);
+				s.append(`\nexports.${key} = ${key};`);
+			}
+		},
+	});
+
+	return s.toString();
+}