promisrFS

promisrFS promisifies the majority of the functions available in the core fs module.

This module just forwards your arguments to the particular function available on the fs module, so check out the spec for more information. Additionally, any optional arguments in the spec are optional here also.

Compatibility

Node Version	Build Status
v6.10.2	TBD

Install

npm install @keymux/promisrfs

yarn add @keymux/promisrfs

Features

Virtually every asynchronous function has been duplicated here with a predictable name.

Examples of predictable names:

fs name	promisrFS name
mkdir	mkdirPromise
readFile	readFilePromise
unlink	unlinkPromise
writeFile	writeFilePromise

Exceptions to predictable names:

fs name	promisrFS name
realpath	realpathPromise
realpath.native	realpath.nativePromise

Common use cases

readFilePromise

Promises to read a file from disk and return the contents.

Example

const { readFilePromise } = require("@keymux/promisrfs");

const path = require("path");

const filename = path.resolve("path/to/file");

const options = {
  encoding: "utf-8",
  flag: "r",
};

return readFilePromise(filename, options)
  .then(contents => {
    console.log(contents);
  }).catch(error => {
    console.error(error);
  });

writeFilePromise

Promises to write a file to disk

Example

const { writeFilePromise } = require("@keymux/promisrfs");

const path = require("path");

const filename = path.resolve("path/to/file");

const contents = "Some text to write";

const options = {
  encoding: "utf-8",
  flag: "r",
};

return writeFilePromise(filename, contents, options)
  .then(() => {
    console.log("Wrote the file successfully to disk");
  }).catch(error => {
    console.error(error);
  });

Where it gets fun

// This example is meant to read a file, perform some transformation
// and write the result

const { readFilePromise, writeFilePromise } = require("@keymux/promisrfs");

const minimist = require("minimist");
const path = require("path");

const inputFile = "input-file";
const outputFile = "output-file";

const argv = minimist(process.argv.slice(2));

[inputFile, outputFile].forEach(ea => {
  if (argv[ea] === undefined) {
    console.error(`--${ea} was missing`);

    const base = path.basename(process.argv[1]);

    console.error("Usage\n" +
      `  ${base} --input-file=path/to/input --output-file=path/to/output`);

    process.exit(-1);
  }
});

// Replaces all instances of A or a with a question mark
const transformation = contents => contents.toString().replace(/[Aa]/g, "?");

// Promise chaining fun
return readFilePromise(argv[inputFile])
  .then(contents => transformation(contents))
  .then(result => writeFilePromise(argv[outputFile], result));