Deep freeze ❄️

deepFreeze.js

/**
* Freeze nested objects
*
* const dude = deepFreeze({ 
*   name: 'John',
*   lastname: 'Doe',
*   address: {
*     street: 'Wall Street',
*     number: '62'
*   }
* })
* 
* dude.address.street = 'Broadway'  // TypeError: Cannot assign to read only property 'name' of object '#<Object>'
**/

const isObject = (val) => val && typeof val === 'object'

function deepFreeze (obj) {
  if (isObject(obj) && !Object.isFrozen(obj)) {
    Object.keys(obj).forEach(name => deepFreeze(obj[ name ]))
    Object.freeze(obj)
  }
  return obj
}