Tbjson-handler NPM

TBJSON Handler

An event handler based off of the standard DOM event chain, but for TBJSON annotated data.

Format

Typed Binary JSON provides a way to describe structured data.
This package follows the TBJSON scheme and provides a way to listen to events (changes) in the structured data.
The typical use case for this package is needing to listen for a change in a complicated tree structure while being performance minded.
All of your classes must derive from the Handler Class.
It is best to have a base Model class that inherits from TbjsonHandler so that you can add common functionality there.

Working Example

import Tbjson from 'typed-binary-json';
import Handler from 'tbjson-handler';

class Model extends Handler {

	// a modelType accessor must be present on all classes
	// modelType will be propagated up to allow for selective listening
	get modelType() {
		return this.constructor.modelType;
	}
}

Model.modelType = 'Model'; // set the value of the protype itself, the getter will source from here

class A extends Model {

	@Handler.prop x = 'string'; // handle when x changes
	@Handler.prop y = 'boolean'; // handle when y changes
	z = [new A(), new A()]

	// handle when this function is called
	@Handler.handle addZ(z) {
		this.z.push(z);
	}
}

A.modelType = 'A';

A.tbjson = {

	// by default all properties in the definition below are listened to, set a property to false here to omit one
	handles: {
		z: false // do not listen to z
	},

	// the TBJSON definition
	definition: {
		x: Tbjson.TYPES.STRING, // a string
		y: Tbjson.TYPES.STRING, // a string
		z: [Tbjson.TYPES.ARRAY, A] // an array of class A
	}
};

class B extends Model {
	a = new A();
}

B.modelType = 'B';

B.tbjson = {
	definition: {
		a: A // a is of class A (above)
	}
};

class C extends Model {
	b = new B();
}

C.modelType = 'C';

C.tbjson = {
	definition: {
		b: B // b is of class B (above)
	}
};

let c = new C();

c.listen(null, null, (e) => console.log(e)); // listen for any event

c.b.a.addZ(new A()); // console will print a TbjsonHandlerEvent (below)

// TbjsonHandlerEvent: {
//     obj: c,
//     path: ['A', 'B', 'C'],
//     objs: [a, b, c],
//     type: undefined,
//     property: undefined,
//     value: undefined
// }

Methods

All classes that inherit from TbjsonHandler (the default and only export of this package) will have the following methods:

inject(parentHandler) => undefined

Inject a handler into the object (will crawl all TBJSON defined properties and also add to those).

handle(e, local) => undefined

Fire an event. If nothing is passed a new TbjsonHandlerEvent will be made for the class. If you've already constructed an event for this class, pass true as arg 2, and the class will not re-add its signature.

listen(nameOrArrayOrFilterFn, propertyNameOrArray, fn) => destroyer()

Attach a listener to an object.

Takes in:

arg 1: a modelType (class name), or array of them, or a filter function
arg 2: a property name or array of them
arg 3: the function to call if an event matches

Decorators

Use these decorators to control how events will be handled.

@Handler.inject

Fire an event everytime this function is called and also inject this into the first argument passed into the function (inject() will be called on the passed object).

@Handler.injectType(type, objArgIndex)

Same as above but also provide a type (string) and optionally an argument number as to which argument needs injection. Type will be a field on the event object that bubbled up.

@Handler.handle

Fire an event everytime this function is called.

@Handler.handleType(type)

Fire an event everytime this function is called and include a type to be addded to the event object that will bubble up.

@Handler.prop

Fire an event everytime the property changes. An event type of changed will always be set on the propogating event.

Visible Data

The only data that will be passed up will be of TbjsonHandlerEvent.

TbjsonHandlerEvent {
	obj: {}, // the source object
	path: [], // an array of string which are the modelTypes (class names)
	obj: [], // the actual objects that correspond to the path above
	type: 'string', // the type of event
	property: 'string', // if a property has changed, the property name
	value: 'any', // if a property has changed, the new property value
}