Esconform NPM | npm.io

esconform

esconform is a JavaScript library that allows you to conform JavaScript objects to an external model.

It allows you to transform the keys of an object, then uses setters to ensure that updated values to the output object are transformed. Both transformation functions can use an external specification to determine the validity of the transformation.

All values besides null and undefined are transformed to their corresponding JavaScript Objects (e.g. this 'string' will be transformed into a new String('string')).

Note: Users have to manually specify that spec values should be returned if actual values are undefined. You can also set mirror: true.

Usage

const specification = {
   firstName: 'string',
   lastName: 'string',
   age: 'number',
}


Object.defineProperty(specification, 'address', { value: {type: 'string'} })

const newModel = new Model({

   values: (key, value, spec) => {
       if (value === undefined) value = spec // Default to the specification (user-defined)
       return value
   },

   keys: (key, spec) => {

       const specVal = spec[key]

       let info = {
           value: key, // Specify the new key
           enumerable: specVal?.enumerable ?? true // Specify enumerability
       }

       // Specify links to the new key
       if (key === 'fullName') {
           info.links = [
               {key: 'firstName', update: (value) => value.split(' ')[0]}, 
               {key: 'lastName', update: (value) => value.split(' ')[1]}, 
           ]
       }

       if (!(key in spec)) delete info.value // Silence key if not in spec

       return info
   },

   specification,
})

const person = {
   fullName: 'John Doe',
   age: 30,
   address: '123 Main St',
   extra: 'THIS IS REALLY ANNOYING'
}

const john = model.apply(
   person,
   {
       mirror: true // Mirror all values in the specification that aren't present on provided value
   }
)

// Properties are transformed based on the specification
console.log('firstName', john.firstName) // Result: John
console.log('lastName', john.lastName) // Result: Doe
console.log('fullName', john.fullName) // Result: undefined

// Properties that are out of the specification are not set
console.log('extra', john.extra, 'extra' in john) // Result: undefined, false

// Properties that are out of the specification will also be blocked
john.extra = 'TEST' // Silenced by Proxy
console.log('extra', john.extra, 'extra' in john) // Result Still: undefined, false

// Linked properties will respond to each other (even if the original key is not in the specification)
john.fullName = 'Jane Doe'
console.log('firstName', john.firstName) // Result: Jane
console.log('lastName', john.lastName) // Result: Doe
console.log('fullName', john.fullName) // Result: undefined

// Properties that are originally missing but present in the specification will be processed
const dob = new Date('1990-01-01')
console.log('DoB', dob) // Result: Sun Dec 31 1989 16:00:00 GMT-0800 (Pacific Standard Time)
john.dateOfBirth = dob
console.log('DoB', john.dateOfBirth) // Result: Sun Dec 31 1989 16:00:00 GMT-0800 (Pacific Standard Time)