Deep observer for Aurelia

deepObserver.ts

/**
 * Created by Jason on 29/02/2016.
 *
 * constructor(public deepobserver:DeepObserver) {
 *   this.obsDisposer = this.deepobserver.observe(this, 'target', (n,o,p)=>
 *                                                    { console.log('DATA CHANGED:', p, ':', o,'===>', n ); }
 *  }
 *  @bindable target:Object;
 *
 *  To remove bindings, call this.obsDisposer();
 */

import {BindingEngine,bindable} from "aurelia-framework";
import {autoinject} from "aurelia-dependency-injection";

@autoinject()
export class DeepObserver {
  private _bindingEngine:BindingEngine;

  constructor(bindingEngine:BindingEngine) {
    this._bindingEngine = bindingEngine;
  }

  public observe(target:Object, property:string, callback:(n:any, o:any, name:string)=>void):()=>void {
    var subscriptions:{ root:any, children:any[] } = { root:null, children:[] };

    subscriptions.root=(this._bindingEngine.propertyObserver(target, property)
        .subscribe((n, o) => {
                        this.disconnect(subscriptions.children);
                        let path = property;
                        this.recurse(target, property, subscriptions.children, callback, path);
                        }
                      )
                     );
    return () => { this.disconnect(subscriptions.children); subscriptions.root.dispose(); }
  }

  private disconnect(subscriptions) {
    while (subscriptions.length) {
      subscriptions.pop().dispose();
    }
  }

  private recurse(target, property, subscriptions, callback, path) {
    let sub = target[property];
    if (typeof sub === "object") {
      for (var p in sub)
        if (sub.hasOwnProperty(p)) {
          this.recurse(sub, p, subscriptions, callback, `${path}${sub instanceof Array ? '['+p+']' : '.'+p}`);
        }
    }
    if (target!=property) // Avoid re-observice root node
    {
      subscriptions.push(this._bindingEngine.propertyObserver(target, property).subscribe((n, o) => callback(n, o, path)));
    }
  };
}