before, after, and around hooks for sync and sync functions
npm install aspectsbefore, after, and around hooks for sync and async functions
also known as aspect-oriented programming
``shell`
npm install --save aspects
`js
const { before, after, around } = require('aspects').sync
const { all: catNames, random: catName } = require('cat-names')
// suppose a function
function hello (name) {
return Hello, ${name}!
}
console.log(hello(catName()))
// Hello, Misty!
// what if we could hook into _before_
// the function runs to check its arguments?
function onlyCats ([name]) {
return (catNames.indexOf(name) !== -1)
? [name]
: new Error(${name} is not a cat name.)
}
console.log(before(hello, onlyCats)(catName()))
// Hello, Bandit!
console.log(before(hello, onlyCats)(reverse(catName())))
// Error: aloL is not a cat name.
// at before.sync (example.js:13:7)
// at before.js:8:17
// at Object.
// or _after_ to change the return value?
function loud (value) {
return value.toUpperCase()
}
console.log(after(hello, loud)(catName()))
// HELLO, SNICKERS!
// or _around_, to wrap the function?
function character (fn, args) {
return fn.apply(null, args.map(a => a[0])) + '!!!'
}
console.log(around(hello, character)(catName()))
// Hello, M!!!!
// utility function
function reverse (str) {
return str.split('').reverse().join('')
}
`
fn is sync function: uses return
hook is function of shape (args) => Error | newArgs
fn is async function: the last argument is an error-first callback
hook is function of shape (args, cb) => cb(Error, newArgs)
fn is sync function: uses return
hook is function of shape (value) => Error | newValue
fn is async function: the last argument is an error-first callback
hook is function of shape (value, cb) => cb(Error, newValue)
fn is sync function: uses return
hook is function of shape (fn, args) => newFn
fn is async function: the last argument is an error-first callback
hook is function of shape (fn, args, cb) => newFn
The Apache License
Copyright © 2016 Michael Williams
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
[stability-badge]: https://img.shields.io/badge/stability-experimental-orange.svg?style=flat-square
[stability-url]: https://nodejs.org/api/documentation.html#documentation_stability_index
[version-badge]: https://img.shields.io/npm/v/aspects.svg?style=flat-square
[version-url]: https://npmjs.org/package/aspects
[test-badge]: https://img.shields.io/travis/ahdinosaur/aspects/master.svg?style=flat-square
[test-url]: https://travis-ci.org/ahdinosaur/aspects
[coverage-badge]: https://img.shields.io/codecov/c/github/ahdinosaur/aspects/master.svg?style=flat-square
[coverage-url]: https://codecov.io/github/ahdinosaur/aspects
[downloads-badge]: http://img.shields.io/npm/dm/aspects.svg?style=flat-square
[downloads-url]: https://npmjs.org/package/aspects
[standard-badge]: https://img.shields.io/badge/code%20style-standard-brightgreen.svg?style=flat-square
[standard-url]: https://github.com/feross/standard