Function load

tools/cli/hooks.js:98–165

(url, context, nextLoad)

}

export async function load(url, context, nextLoad) {
  const [urlWithoutQuery] = url.split('?');

  if (!urlWithoutQuery.startsWith('file:')) {
    return nextLoad(url, context);
  }

  const filePath = fileURLToPath(urlWithoutQuery);
  if (!TS_EXTENSIONS.has(path.extname(filePath))) {
    return nextLoad(url, context);
  }

  const stat = await fs.promises.stat(filePath);
  const cached = transformCache.get(filePath);
  if (cached?.mtimeMs === stat.mtimeMs) {
    return {
      format: cached.format,
      source: cached.source,
      shortCircuit: true,
    };
  }

  const sourceText = await fs.promises.readFile(filePath, 'utf8');
  const isCommonJs = filePath.endsWith('.cts');
  const moduleType = isCommonJs ? 'commonjs' : 'es6';
  const tsx = filePath.endsWith('.tsx');

  let output;
  try {
    output = await transform(sourceText, {
      filename: filePath,
      sourceMaps: 'inline',
      module: { type: moduleType },
      jsc: {
        target: 'es2022',
        keepClassNames: true,
        experimental: { keepImportAttributes: true },
        parser: {
          syntax: 'typescript',
          tsx,
          decorators: true,
          dynamicImport: true,
        },
        transform: {
          legacyDecorator: true,
          decoratorMetadata: true,
          useDefineForClassFields: false,
          react: tsx
            ? { runtime: 'automatic', importSource: 'react' }
            : undefined,
        },
      },
    });
  } catch (error) {
    const detail = error instanceof Error ? error.message : String(error);
    throw new Error(`[swc-loader] Failed to compile ${filePath}\n${detail}`);
  }