Parse esm dist to add file extensions on imports/export

Author: micantoine

tasks/parser.js

@@ -0,0 +1,58 @@
+/* eslint-disable no-shadow */
+/* eslint-disable @typescript-eslint/no-var-requires */
+const fs = require('fs');
+const path = require('path');
+const { Parser } = require('acorn');
+const { walk } = require('svelte/compiler');
+const MagicString = require('magic-string');
+
+const parseDir = (dir) => {
+  fs.readdir(dir, (err, children) => {
+    if (err) return
+    children.forEach((child) => {
+      const pathname = `${dir}/${child}`;
+      fs.lstat(pathname, (err, stats) => {
+        if (err) return
+        if (stats.isDirectory()) {
+          parseDir(pathname);
+        }
+        if (stats.isFile()) {
+          fs.readFile(pathname, 'utf-8', (err, content) => {
+            if (err) return
+            const ast = Parser.parse(content, {
+              ecmaVersion: 'latest',
+              sourceType: 'module'
+            });
+            const magicContent = new MagicString(content);
+            walk(ast, {
+              enter(node) {
+                if (['ImportDeclaration', 'ExportNamedDeclaration', 'ExportAllDeclaration'].includes(node.type) && node.source) {
+                  const filename = path.resolve(path.dirname(pathname), `${node.source.value}.js`);
+                  const dirIndex = path.resolve(path.dirname(pathname), `${node.source.value}/index.js`);
+                  if (fs.existsSync(filename)) {
+                    magicContent.prependLeft(node.source.end - 1, '.mjs');
+                  } else if (fs.existsSync(dirIndex)) {
+                    magicContent.prependLeft(node.source.end - 1, '/index.mjs');
+                  }
+                } else if (
+                  node.type === 'ExportDefaultDeclaration'
+                  && node.declaration?.left?.type === 'MemberExpression'
+                  && node.declaration.left.object.name === 'module'
+                  && node.declaration.left.property.name === 'exports'
+                ) {
+                  magicContent.remove(node.declaration.left.start, node.declaration.right.start);
+                }
+              }
+            });
+            const mjsPathname = pathname.replace('/esm', '').replace('.js', '.mjs');
+            fs.writeFile(mjsPathname, magicContent.toString(), (err) => {
+              if (err) throw err;
+            });
+          });
+        }
+      });
+    });
+  });
+}
+
+parseDir('./dist/esm');