keyblade

Fail fast when accessing undefined properties on objects.

Installation

This is not the library you need. This is the library you deserve!

npm install keyblade --save

Requires Node v6 or above.

Usage

const { keyblade, UndefinedKeyError } = require('keyblade')

// Object to protect
const unsafe = {
  hello: 'world'
}

console.log(unsafe.hello)
// < 'world'
console.log(unsafe.goodbye)
// < undefined

// Create a protected version (does not modify `unsafe`)
const safe = keyblade(unsafe)

console.log(safe.hello)
// < 'world'
console.log(safe.goodbye)
// < UndefinedKeyError: The key 'goodbye' does not exist on the object.

Note: to ensure interoperability with utilities that use Symbols, checking them has been disabled. This means using util.inspect and JSON.stringify works without issues. I don't know why you would need to stringify a protected object but... you can!

Why do I need deserve it?

Glad you asked! Heard of those wonderful things we call environment variables? They're fun! Even more so when someone forgets to define them.

const env = process.env

const cert = someModuleThatNeedsACertFile(env.CERT_FILE_PATH)

// Later...

// < Error: something about strings or buffers I dunno man..

Of course, you could be all like..

if (!env.CERT_FILE_PATH) throw new Error('No CERT_FILE_PATH specified')

Now repeat that 43 times. Or, you could use keyblade!

const { keyblade } = require('keyblade')
const env = keyblade(process.env)

const cert = someModuleThatNeedsACertFile(env.CERT_FILE_PATH)
// < UndefinedKeyError: The key 'CERT_FILE_PATH' does not exist on the object.

One could even get fancy and customize the error message.

const env = keyblade(process.env, {
  message: (key) => `Environment variable ${key} is not set.`
})

const cert = someModuleThatNeedsACertFile(env.CERT_FILE_PATH)
// < UndefinedKeyError: Environment variable CERT_FILE_PATH is not set.

If you are not a fan of the console.error happening before throwing, you can either customize it:

const env = keyblade(process.env, {
  message: (key) => `Environment variable ${key} is not set.`,
  logBeforeThrow: (message, key) => mylogger.error(message, 'key was ' + key)
})

Or disable it entirely.

const env = keyblade(process.env, {
  message: (key) => `Environment variable ${key} is not set.`,
  logBeforeThrow: false
})

Contributing

npm run scripts

• npm run test: Runs tests once
• npm run test-watch: Runs tests in watch-mode
• npm run lint: Lints the code once
• npm run lint-watch: Lints the code in watch-mode
• npm run cover: Runs code coverage using nyc (istanbul)
• npm run coveralls: Used by coveralls

Author

Jeff Hansen - @Jeffijoe