Keypath object idea

getKeypath.js

import normaliseKeypath from 'shared/normaliseKeypath';

var cache = {}, Keypath;

Keypath = function ( str ) {
  this.str = str;
  this.keys = this.str.split( '.' );
  
  this.last = this.keys[ this.keys.length - 1 ];
  
  if ( this.keys.length > 1 ) {
    this.parent = new Keypath( this.keys.slice( 0, -1 ).join( '.' ) );
  } else {
    this.parent = null;
  }
};

Keypath.prototype = {
  toString: function () {
    return this.str;
  }
};

export default function getKeypath ( str ) {
  str = normaliseKeypath( str ); // foo[0] -> foo.0
  return ( cache[ str ] || ( cache[ str ] = new Keypath( str ) );
}

L12: this.parent = getKeypath( this.keys.slice( 0, -1 ).join( '.' ) );?

kp1 = getKeypath('foo.1.name')
kp2 = getKeypath('foo.1.title')
kp3 = getKeypath('foo.1')
kp3.update(1 /*index*/, 3 /*value*/)

kp1.toString()
// foo.3.name