\n | \n [options]\n | \n \n object
\n string
\n null
\n | \n \n \n An optional options object or a value indicating an encoding. If\n passed as an object, the following properties are are accepted as\n options:\n \n \n - \n encoding -
string | null - An\n \n encoding supported by Node.js or null to indicate\n no encoding. Defaults to null.\n \n - \n thisArg -
any - The value of\n this within callback. Defaults to\n undefined.\n \n \n \n If passed as a string or null, it is interpreted as the\n encoding option.\n \n \n If no encoding is given, callback is called with a\n Buffer object containing the contents of the file.\n Otherwise, it is called with a string created with\n \n buffer.toString(encoding).\n \n | \n
\n \n | \n callback\n | \n \n function\n | \n \n \n A function that transforms the contents of each file. It is invoked\n with two arguments:\n \n \n - \n contents -
Buffer | string - The\n contents of the file. If no encoding is given, contents\n will be a Buffer; otherwise, it will be a string.\n \n - \n file -
File - The\n \n File object whose contents are being transformed.\n Use this to access metadata about the file, e.g., its filename.\n \n \n \n The contents of the file are replaced with the return value of the\n callback. For asynchronous transformations, a\n \n Promise may be returned. The return or completion\n value must have the same type as contents.\n \n \n The value of this within the callback may be set with the\n thisArg option; otherwise, this will be\n undefined.\n \n | \n
\n