Function getJavascriptTransformFunction

src/util/transform.ts:71–92

* Retrieves a JavaScript transform function from a file. * @param filePath - The path to the JavaScript file. * @param functionName - Optional name of the function to retrieve. * @returns A Promise resolving to the requested function. * @throws Error if the file doesn't export a valid function.

(
  filePath: string,
  functionName?: string,
)

 * @throws Error if the file doesn't export a valid function.
 */
async function getJavascriptTransformFunction(
  filePath: string,
  functionName?: string,
): Promise<Function> {
  const requiredModule = await importModule(filePath);

  // Validate that functionName is an own property to prevent prototype pollution attacks
  if (
    functionName &&
    Object.prototype.hasOwnProperty.call(requiredModule, functionName) &&
    typeof requiredModule[functionName] === 'function'
  ) {
    return requiredModule[functionName];
  } else if (typeof requiredModule === 'function') {
    return requiredModule;
  } else if (requiredModule.default && typeof requiredModule.default === 'function') {
    return requiredModule.default;
  }
  throw new Error(
    `Transform ${filePath} must export a function, have a default export as a function, or export the specified function "${functionName}"`,
  );
}

/**
 * Creates a function that runs a Python transform function.