Smart Promise

Smart Promise is a Promise extension that provides filtered catch handler.

[![license][license-img]][license-url]
[![release][release-img]][release-url]
[![semantic][semantic-img]][semantic-url]

Benchamrks

[latest results][]

`` text
bluebird x 3,541 ops/sec ±1.70% (82 runs sampled)
smart-promise x 99,766 ops/sec ±1.24% (86 runs sampled)
`

Install

` bash
npm install smart-promise
`

API

The same native [Promise API][] applies, the only difference is the catch() method.

$3

Behaves normally as per the native [Promise API][1]

$3

A filtered variant of catch (like other non-JS languages typically have) that lets you only handle specific errors.

The catch handler that is first met that has eligible constructors specified, is the one that will be called.

###### Example

Extend your existing Promise Libraries:

` js
const { Smart } = require('smart-promise')

const Promise = Smart(MyPromiseLib)

// or, use the shorthand
const Promise = require('smart-promise')(MyPromiseLib)
`

Standalone:

` js
const { Promise } = require('smart-promise')
`

` js
Promise
.then(_ => return a.b.c.d())

.catch(TypeError, error => {
// If the error is a "TypeError", this code block will execute
})

.catch(ReferenceError, error => {
// If the error is a "ReferenceError", this code block will execute instead
})

.catch('TypedErrorName', error => {
// If the error constructor matches "TypedErrorName", this code block will execute instead
})

.catch(error => {
// Generic catch-the rest (error wasn't TypeError nor ReferenceError)
})
`

You may also add multiple filters for a catch handler:

` js
Promise
.then(_ => return a.b.c.d())

.catch(TypeError, ReferenceError, error => {
// Will end up here on programmer error
})

.catch(NetworkError, TimeoutError, 'SomeError', error => {
// Will end up here on expected everyday network errors
})

.catch(error => {
// Catch any unexpected errors
})
`

You can also wrap it around existing promises resolvers, this is useful for managing 3rd party generated promises:

` js
const { Promise } = require('smart-promise')
const Library = require('some-other-promise-producting-library')

Promise.resolve(Library.action())
.catch('SomeError', error => {})
`

ESlint

If you're using ESlint or similar tooling, please refer to [prefer-promise-reject-errors][]

[latest results]: https://github.com/ahmadnassri/benchmark-node-promise-catch
[Promise API]: https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Promise
[1]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/catch
[prefer-promise-reject-errors`]: https://eslint.org/docs/rules/prefer-promise-reject-errors

----
> Author: Ahmad Nassri •
> Twitter: @AhmadNassri

[license-url]: LICENSE
[license-img]: https://badgen.net/github/license/ahmadnassri/node-smart-promise

[release-url]: https://github.com/ahmadnassri/node-smart-promise/releases
[release-img]: https://badgen.net/github/release/ahmadnassri/node-smart-promise

[semantic-url]: https://github.com/ahmadnassri/node-smart-promise/actions?query=workflow%3Arelease
[semantic-img]: https://badgen.net/badge/📦/semantically%20released/blue