Get nested json diff. this is just initial version to store for later use.

diff_helper.ts

module helpers {
  'use strict';

  export class DiffHelper {


    public diff(a, b, seed = {}) {

      const keys = this.arrayUnique(Object.keys(a).concat(Object.keys(b)));

      return keys.reduce((delta = {}, key) => {
        if (a.hasOwnProperty(key) && b.hasOwnProperty(key)) {
          // both has property
          const type = typeof a[key];
          if (type === 'object') {
            // if has children, calculate diff
            const childDelta = this.diff(a[key], b[key]);
            if (childDelta !== undefined && Object.keys(childDelta).length > 0) {
              delta[key] = childDelta;
            }
          } else if (type !== 'function' && a[key] !== b[key]) {
            // skip function function and set value
            delta[key] = b[key];
          }
        } else if (a.hasOwnProperty(key) && !b.hasOwnProperty(key)) {
          // property has removed
          delta[key] = undefined;
        } else if (!a.hasOwnProperty(key) && b.hasOwnProperty(key)) {
          // property has added
          delta[key] = b[key];
        }
        if (Object.keys(delta).length > 0) {
          return delta;
        } else {
          return undefined;
        }
      }, seed);
    }
        private arrayUnique(a) {
      return a.reduce(function(p, c) {
        if (p.indexOf(c) < 0) p.push(c);
        return p;
      }, []);
    };


  }
}