@idan-loo/middleware

middleware

Create your own middlewares to divide a large logic into serveral wares.

It is inspired by the middleware system of Koa

Install

# with npm
npm install --save @idan-loo/middleware
# with yarn
yarn add @idan-loo/middleware

Usage

import { compose } from '@idan-loo/middleware'

const mw1 = async (ctx, next) => {
  ctx.name = 'mw1'
  await next()
}

const mw2 = async (ctx, next) => {
  ctx.name = 'mw2'
  await next()
}

const mw3 = async (ctx, next) => {
  ctx.name = 'mw3'
  await next()
}

const exec = compose(
  mw1,
  mw2,
  mw3
)
await exec({ name: 'test' })

Middleware

Each middleware should return a Promise object. You can simply add an async keyword in front of the function declation, or just return next().

import { Next } from '@idan-loo/middleware'

type Context = {
  name: string,
}

const mw1 = async (ctx: Context, next: Next) => {
  ctx.name = 'mw1'
  return next()
}

const mw2 = async (ctx: Context, next: Next) => {
  ctx.name = await anAsyncAction()
  await next()
}

const mw3 = async (ctx: Context, next: Next) => {
  await next()
  ctx.name = 'after next'
}

If you want to go on executing the next middlewares, you should call next() manually.

import { compose } from '@idan-loo/middleware'

const mw1 = async (ctx: Context, next: Next) => {
  ctx.name = 'mw1'
  return next()
}

const mw2 = async (ctx: Context) => {
  ctx.name = 'mw2'
}

const mw3 = async (ctx: Context, next: Next) => {
  ctx.name = 'mw3'
  return next()
}

// mw3 won't be executed because mw2 doesn't call the next method
const exec = compose(
  mw1,
  mw2,
  mw3
)
exec({ name: 'test' })

Each calling of compose returns a middleware as well, so you can combine several middlewares by simply calling the compose method

import { compose } from '@idan-loo/middleware'

const checkAuthed = async (ctx, next) => {
  // Go next only if the `ctx.isAuthed` is true
  if (ctx.isAuthed) {
    return next()
  }
}

const getSomePrivacy = async (ctx, next) => {
  /* Do some things */
  return next()
}

/* 
   Combine the `getSomePrivacy` with the `checkAuthed`.
   `checkAuthed` can be reused in everywhere you need.
 */
const getSomePrivacyIfAuthed = compose(
  checkAuthed,
  getSomePrivacy
)

const exec = compose(
  getSomePrivacyIfAuthed,
  handleThePrivacy
)
await exec(ctx)