readFile

How does readFile work?

Asynchronously reads the entire contents of a file.

If no encoding is specified (using options.encoding), the data is returned as a Buffer object. Otherwise, the data will be a string.

If options is a string, then it specifies the encoding.

When the path is a directory, the behavior of fsPromises.readFile() is platform-specific. On macOS, Linux, and Windows, the promise will be rejected with an error. On FreeBSD, a representation of the directory's contents will be returned.

Usage

An example of reading a package.json file located in the same directory of the running code:

import {readFile} from "universal-fs";
try {
  const filePath = new URL("./package.json", import.meta.url);
  const contents = await readFile(filePath, {encoding: "utf8"});
  console.log(contents);
} catch (err) {
  console.error(err.message);
}

It is possible to abort an ongoing readFile using an AbortSignal. If a request is aborted the promise returned is rejected with an AbortError:

import {readFile} from "universal-fs";
 
try {
  const controller = new AbortController();
  const {signal} = controller;
  const promise = readFile(fileName, {signal});
 
  // Abort the request before the promise settles.
  controller.abort();
 
  await promise;
} catch (err) {
  // When a request is aborted - err is an AbortError
  console.error(err);
}

Additional details

Aborting an ongoing request does not abort individual operating system requests but rather the internal buffering fs.readFile performs.

Any specified FileHandle has to support reading.

• since universal-fs v1.0.0 | Node.js v10.0.0
• param path filename or FileHandle
• param options Read options
• return Fulfills with the contents of the file.