Function loadTsconfig

src/tsconfig-loader.ts:115–165

(
  configFilePath: string,
  // eslint-disable-next-line no-shadow
  existsSync: (path: string) => boolean = fs.existsSync,
  readFileSync: (filename: string) => string = (filename: string) =>
    fs.readFileSync(filename, "utf8")
)

}

export function loadTsconfig(
  configFilePath: string,
  // eslint-disable-next-line no-shadow
  existsSync: (path: string) => boolean = fs.existsSync,
  readFileSync: (filename: string) => string = (filename: string) =>
    fs.readFileSync(filename, "utf8")
): Tsconfig | undefined {
  if (!existsSync(configFilePath)) {
    return undefined;
  }

  const configString = readFileSync(configFilePath);
  const cleanedJson = StripBom(configString);
  let config: Tsconfig;
  try {
    config = JSON5.parse(cleanedJson);
  } catch (e) {
    throw new Error(`${configFilePath} is malformed ${e.message}`);
  }

  let extendedConfig = config.extends;
  if (extendedConfig) {
    let base: Tsconfig;

    if (Array.isArray(extendedConfig)) {
      base = extendedConfig.reduce(
        (currBase, extendedConfigElement) =>
          mergeTsconfigs(
            currBase,
            loadTsconfigFromExtends(
              configFilePath,
              extendedConfigElement,
              existsSync,
              readFileSync
            )
          ),
        {}
      );
    } else {
      base = loadTsconfigFromExtends(
        configFilePath,
        extendedConfig,
        existsSync,
        readFileSync
      );
    }

    return mergeTsconfigs(base, config);
  }
  return config;
}

/**
 * Intended to be called only from loadTsconfig.