Using ES6 proxy with arrays.

proxy.js

/* jshint esnext:true */

function get( target, prop, receiver ) {
  console.log( 'target: ' + target );
  console.log( 'property: ' + prop );
//   console.log( 'Receiver: ' + receiver );
  return Reflect.get( target, prop, receiver );
}

var handler = {
  'get': get
};

// Create a proxy for a plain array:
var proxy = new Proxy( [1,2,3,4,5], handler );

console.log( 'Result => beep: ' + proxy.beep );
console.log( 'Result => -123: ' + proxy[ -123] );
console.log( proxy.fill( 1 ) );
console.log( 'Result => 0: ' + proxy[ 0 ] );

// Set the prototype of a plain array to the proxy, based on the premise that the prototype of an array is an array...
var arr1 = [ 10, 20, 30, 40, 50 ];
Object.setPrototypeOf( arr1, proxy );

console.log( 'Result => beep: ' + arr1.beep );
console.log( 'Result => -123: ' + arr1[ -123 ] );
console.log( arr1.fill( 100 ) );
console.log( 'Result => 0: ' + arr1[ 0 ] );

// // Subclass a proxy...
// function ArrayProxy() {}
// ArrayProxy.prototype = proxy;

// class Arr extends ArrayProxy {
//   constructor( x ) {
//     super( x );
//   }
// }

// var arr2 = new Arr();

// console.log( arr2.beep );
// console.log( arr2[ -123] );
// console.log( arr2.fill( 99 ) );
// console.log( arr2[ 0 ] );