code that automatically adds .js at the end of import/from

fix-esm.js

import { glob } from 'glob'
import { readFile, writeFile } from 'fs/promises'
import path from 'path';

export function addFileExtension(importStatement) {
    const staticImportRegex = /(import\s+(?:.+\s+from\s+)?['"])(\.\/[^'\"]+)(?<!\.js)(['"])/g;
    const dynamicImportRegex = /(import\(['"])(\.\/[^'\"]+)(?<!\.js)(['"]\))/g;
    const reexportRegex = /(export .+ from ['"])(\.\/[^'\"]+)(?<!\.js)(['"])/g;

    importStatement = importStatement.replace(staticImportRegex, "$1$2.js$3");
    importStatement = importStatement.replace(dynamicImportRegex, "$1$2.js$3");
    importStatement = importStatement.replace(reexportRegex, "$1$2.js$3");

    return importStatement;
}

export async function getJsFiles(config = {}) {
    let includePattern = config.include || '**/*.js';
    let excludePattern = config.exclude || [];
    excludePattern.push('**/node_modules/**');

    excludePattern = excludePattern.length > 1 ? `{${excludePattern.join(',')}}` : excludePattern[0];

    const root = path.join(process.cwd(), config.rootDir) || '';
    const files = await glob(includePattern, { ignore: excludePattern, cwd: root });

    for (let f of files) {
        const file = path.join(root, f);
        const code = addFileExtension(await readFile(file, 'utf8'))
        await writeFile(file, code)
    }
}