obext — ES6+ Object Extensions

Reactive property definitions for JavaScript objects — change events, value transformers, defaults, aliases, and read-only computed properties via Object.defineProperty.

Install

npm install obext

Quick Start

const { prop, field, read_only, get_set } = require('obext');

// reactive property with default + change callback
const obj = { raise(name, e) { /* event bus */ } };
prop(obj, 'temperature', 20, (e) => {
    console.log(`${e.old} → ${e.value}`);
});
obj.temperature = 25; // logs: "20 → 25"

// field — stores on obj._  (serialisable)
field(obj, 'label', 'Untitled');
obj._.label; // 'Untitled'

// read-only computed property
read_only(obj, 'area', () => obj._w * obj._h);

// raw getter/setter with aliases
let _v = 0;
get_set(obj, ['width', 'w'], () => _v, (v) => { _v = v; });

Exports

| Export | Alias | Purpose | |---|---|---| | prop | — | Reactive property with closure storage, change events, transforms, defaults, aliases | | field | — | Reactive property stored on obj._, change events, transforms, defaults | | read_only | ro | Getter-only property | | get_set | gs | Raw getter/setter pair | | opts | — | Module options: { raise_change_events: true } |

Requirements

• Node.js ≥ 12.0.0
• Dependency: lang-mini (utility functions)

Documentation

Full documentation is available in the docs/ folder:

1. Introduction
2. Installation & Quick Start
3. prop — Deep Dive
4. field — Deep Dive
5. Read-Only Properties
6. Get/Set Properties
7. Module Options
8. Ecosystem Integration
9. Agent Reference

Part of a Wider System

obext is a low-level building block primarily consumed by:

• jsgui3-html — UI control framework (every control uses prop/field for reactive state)
• jsgui3-gfx-core — Pixel buffer and shape classes
• ta-tensor — Tensor analysis library
• lang-tools — Data model layer

These upstream modules expect obext to export the exact API surface listed above.

License

MIT © James Vickers