defer

415 bytes

Usage

The defer function allows you to run an async function while registering cleanup functions that will execute after it completes. This is useful when you need to clean up resources regardless of whether the main function succeeds or fails, similar to a finally block.

The function passed to defer receives a register function as its argument. Use this to register cleanup work that should run after the main function finishes.

By default, if a cleanup function throws an error after the main function has thrown an error, the cleanup error will be ignored. You can customize this behavior by passing { rethrow: true } to the register function to have it rethrow cleanup errors instead.

Clean up temporary files

import * as _ from 'radashi'

// Placeholder functions
const createBuildDir = async () => {
  console.log('Creating build directory...')
  await _.sleep(100)
  console.log('Build directory created.')
  return 'build'
}
const build = async () => {
  console.log('Building project...')
  await _.sleep(100)
  console.log('Project built.')
}

await _.defer(async cleanup => {
  const buildDir = await createBuildDir()

  cleanup(() => fs.unlink(buildDir))

  await build()
})

Clean up resources in an API

// Placeholder API
const api = {
  org: {
    create: async () => ({ id: 1 }),
    delete: async () => {
      console.log('Deleting organization...')
      await _.sleep(100)
      console.log('Deleted organization.')
    },
  },
  user: {
    create: async () => ({ id: 2 }),
    delete: async () => {
      console.log('Deleting user...')
      await _.sleep(100)
      console.log('Deleted user.')
    },
  },
}

// Placeholder test function
const executeTest = async () => {
  console.log('Executing test...')
  await _.sleep(100)
  console.log('Test complete.')
}

await _.defer(async register => {
  const org = await api.org.create()
  register(async () => api.org.delete(org.id), { rethrow: true })

  const user = await api.user.create()
  register(async () => api.user.delete(user.id), { rethrow: true })

  await executeTest(org, user)
})