Package Exports

makepromise
makepromise/es5/src

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Readme

makepromise

Make native Promise from a function with a callback.

`makePromise(fn:Function(...args, cb:Function(err:Error, res:any))) => Promise<any>`

Create a promise from a function which accepts a callback as the last argument, and where the callback will be called with 2 arguments: (error, result).

For example, you can unlink a file (here, a temp file is created with wrote package):

import { unlink } from 'fs'
import { createWritable } from 'wrote'
import makePromise from 'makepromise'

let file
(async () => {
  // create a temp file and open a writable stream
  const ws = await createWritable()
  const { path: file } = ws // /var/folders/s0/tmp/T/wrote-69822.data
  // here, just close the stream without makepromise, because it's a different
  // kind of constructor, ie. resolve-reject and not error callback handlers
  await new Promise((resolve, reject) => {
    ws.once('close', resolve)
    ws.once('error', reject)
    ws.close()
  })
  await makePromise(unlink, file)
})()

In addition, errors will be updated to include the stack trace of when makePromise was called, rather than have node internal error stack, or no stack at all:

import { unlink } from 'fs'
import makePromise from 'makepromise'

(async () => {
  try {
    await makePromise(fs.unlink, 'error-test-file')
  } catch ({ stack }){
    console.log(stack)
    /*
    Error: ENOENT: no such file or directory, unlink 'error-test-file'
        at cb (makepromise/src/index.js:28:31)
        at makePromise (makepromise/src/index.js:18:16)
        at Object.<anonymous> (makepromise/examples/error-stack.js:4:1)
    */      // without this feature:
    /*
    Error: ENOENT: no such file or directory, unlink 'error-test-file'
    */
  }
})()

`makePromise(fn:Function(...args, cb:Function(err:Error, res:any), resolveValue:any)) => Promise<any>`

Pass resolveValue as second argument to make promise be resolved with it.

import { unlink } from 'fs'
import { createWritable } from 'wrote'
import makePromise from 'makepromise'

(async () => {
  // create a temp file and open a writable stream
  const ws = await createWritable()
  await closeWritable(ws)
  const { path: file } = ws
  console.log(file) // /var/folders/s0/tmp/T/wrote-69822.data
  // pass 3rd argument as the return value
  const resolvedFile = await makePromise(unlink, file, file)
  console.log(resolvedFile === file) // true
})()

More examples

Check test/spec/integration for the following tests:

How to unlock a file with lockfile package
How to write to a writable stream
How to unlink a file with fs.unlink
How to read stat with fs.stat
How to catch errors after call fs.stat with non-existent file)

ES5

DO NOT USE THIS. USE NEWER NODE.JS The package uses some newer language features. For your convenience, it's been transpiled to be compatible with Node 4. You can use the following snippet.

const makePromise = require('makepromise/es5')

Licence: MIT

(c) Art Deco Code 2018