Node.js utils to deal with async/await.

Installation

npm install --save mono-utils

Usage

INFO: You need node >= 8.0.0 to use mono-utils since it uses native async/await

const { ok, cb, waitFor, ... } = require('mono-utils')

Utils

• ok
• cb
• waitFor
• waitForEvent
• asyncObject
• asyncMap
• asyncForEach

ok

Waits for the value of the Promise and returns its value. If the promise throws an Error, returns undefined.

ok(promise: Object): Promise

Example:

const { ok } = require('mono-core/utils')
const { readFile } = require('fs-extra')

// readFile sends back a Promise since we use fs-extra
const file = await ok(readFile('./my-file.txt', 'utf-8'))

if (file) console.log('File found:', file)

cb

Calls a function Node style function as first argument function (err, result), all the others arguments will be given to the function. Waits for the callback result, throws an Error if err is truthy.

cb(fn: Function, ...args: any[]): Promise

Example:

const { ok } = require('mono-core/utils')
const fs = require('fs')

try {
  const file = await cb(fs.readFile, '/path/to/my/file.txt', 'utf-8')
} catch (err) {
  // Could not read file
}

waitFor

Waits for ms milliseconds to pass, use setTimeout under the hood.

waitFor(ms: number): Promise

Example:

const { waitFor } = require('mono-core/utils')

await waitFor(1000) // wait for 1s

waitForEvent

Waits for emitter to emit an eventName event.

waitForEvent(emitter: EventEmitter, eventName: string, timeout: number = -1): Promise<Array>

Example:

const { waitFor } = require('mono-core/utils')

await waitForEvent(sever, 'listen')

asyncObject

Waits for all Promises in the keys of obj to resolve.

asyncObject(obj: Object): Promise<Object>

Example:

const { asyncObject } = require('mono-core/utils')

const { pictures, comments, tweets } = await asyncObject({
  pictures: getPictures(),
  comments: getComments(),
  tweets: getTweets()
})

console.log(pictures, comments, tweets)

asyncMap

Waits for all Promises mapped by fn:

asyncMap(array: Array, fn: Function): Promise<Array>

Example:

const { asyncMap } = require('mono-core/utils')

const posts = await asyncMap([1, 2, 3], (id) => fetchPost(id))

asyncForEach

Loop for every item in array and call fn and wait for it to finish in series:

asyncForEach(array: Array, fn: Function): Promise<void>

Example:

const { asyncMap } = require('mono-core/utils')

const posts = await asyncForEach(users, async (user) => {
  await saveUser(user)
})

Other utils

We developed other utils that you might find useful:

• mongodb-utils
• elasticsearch-utils
• mono-test-utils