Type-R is the modern JS data framework to manage complex domain and UI application state. Features:

• It's mapped to JSON by default. The mapping can handle sophisticated scenarios with nested JSON and relations by id, and can be easily customized for every particular attribute or class.
• All changes are observable, happens in the scope of transactions, and there's the fine-grained change events system.
• Validation is performed on the first access to the validation error and never happens twice for unchanged data.
• Everything is typed at run-time and is protected from improper updates. The shape of generated JSON and data classes is guaranteed to match the definitions.
• It still looks like regular JS classes and is freaking fast. Type-R data structures are about 10 times faster than Backbone models and collections.

Data layer is defined as a superposition of three kinds of building blocks:

• Record classes with typed attributes.
• Ordered collections of records.
• Stores are records with a set of collections in its attributes used to resolve id-references in JSON.
• IOEndpoints is an entity encapsulating I/O transport which represent the persistent collection of records.

Type-R is completely unopinionated on the client-server transport protocol and the view layer technology. It's your perfect M and VM in modern MVVM or MVC architecture.

import { define, Record } from 'type-r'

// Define email attribute type with encapsulated validation check.
const Email = String.has.check( x => x! || x.indexOf( '@' ) >= 0, 'Invalid email' );

@define class User extends Record {
    static attributes = {
        name  : String.isRequired, // should not be empty for the record to be valid.
        email : Email.isRequired
    }
}

@define class Message extends Record {
    static attributes = {
        created : Date //  = new Date()
        author  : User, // aggregated User record.
        to      : User.Collection, // aggregating collection of users
        subject : '',
        body    : ''
    }
}

const msg = new Message();
assert( !msg.isValid() ); // Is not valid because msg.author has empty attributes

// Listen for the changes in aggregation tree...
msg.on( 'change', () => console.log( 'change!!!' ) );

msg.transaction( () => { // Prepare to make the sequence of changes on msg
    msg.author.name = 'John Dee'; // No 'change' event yet as we're in the transaction. 
    msg.author.email = 'dee@void.com'; 

    assert( msg.isValid() ); // Now msg is valid as all of its attributes are valid.
}); // Got single 'change!!!' message in the console.

Is packed as UMD and ES6 module. No peer dependencies are required.

npm install type-r --save-dev