n9-node-utils

Neo9 Node Utils Module.

Installation

npm install --save @neo9/n9-node-utils

Contents

• N9Error
• ok
• cb
• waitFor
• waitForEvent
• asyncObject

N9Error

Custom error class (extends Error), used by n9-node-micro for API errors with status code and context.

new N9Error(message [, statusCode] [, context])

Arguments:

• message: String, required
• status: Number, default: 500
• context: Object, default: {}

Example:

import { N9Error } from '@neo9/n9-node-utils'

throw new N9Error('file-not-found', 404, { path: '/tmp/my-file.txt' })

ok

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

ok(promise: Object): Promise

Arguments:

• promise: Promise

Example:

import { readFile } from 'fs-extra'
import { ok } from '@neo9/n9-node-utils'

// 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 fn that takes arguments args and an (err, result) callback. Waits for the callback result, throwing an Error if err is truthy.

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

Arguments:

• fn: Function, a function that takes a callback
• args: (...any) arguments to pass to fn

Example:

import { cb } from '@neo9/n9-node-utils'

const file = await cb(readFile('./my-file.txt', 'utf-8'))

console.log('File content:', file)

waitFor

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

waitFor(ms: number): Promise

Arguments:

• ms: Number, default: 0

Example:

import { waitFor } from '@neo9/n9-node-utils'

await waitFor(1000) // wait for 1s

waitForEvent

Waits for emitter to emit an eventName event.

waitForEvent(emitter: EventEmitter, eventName: string): Promise<Array>

Arguments:

• emitter: EventEmitter
• eventName: String

Example:

import { waitForEvent } from '@neo9/n9-node-utils'

await waitForEvent(sever, 'listen')

asyncObject

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

asyncObject(obj: Object): Promise<Object>

Arguments:

• obj: Object, default: {}

Example:

import { asyncObject } from '@neo9/n9-node-utils'

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

console.log(results.pictures, results.comments, results.tweets)