es-shimsobject.getprototypeof 
An ES5 mostly-spec-compliant Object.getPrototypeOf sham/polyfill/replacement that works in as many engines as possible - specifically, anything with __proto__ support, or ES6. Built-in types will also work correctly in older engines.
This package implements the es-shim API interface. It works in an ES3-supported environment and complies with the spec.
Example
var getPrototypeOf = require('object.getprototypeof');
var assert = require('assert');
assert.equal(getPrototypeOf(true), Boolean.prototype);
assert.equal(getPrototypeOf(42), Number.prototype);
assert.equal(getPrototypeOf(''), String.prototype);
assert.equal(getPrototypeOf(/a/g), RegExp.prototype);
assert.equal(getPrototypeOf(new Date()), Date.prototype);
assert.equal(getPrototypeOf(function () {}), Function.prototype);
assert.equal(getPrototypeOf([]), Array.prototype);
assert.equal(getPrototypeOf({}), Object.prototype);var getPrototypeOf = require('object.getprototypeof');
var assert = require('assert');
/* when Object.getPrototypeOf is not present */
delete Object.getPrototypeOf;
var shimmed = getPrototypeOf.shim();
assert.equal(shimmed, getPrototypeOf.getPolyfill());
assert.equal(Object.getPrototypeOf(true), Boolean.prototype);
assert.equal(Object.getPrototypeOf(42), Number.prototype);
assert.equal(Object.getPrototypeOf(''), String.prototype);
assert.equal(Object.getPrototypeOf(/a/g), RegExp.prototype);
assert.equal(Object.getPrototypeOf(new Date()), Date.prototype);
assert.equal(Object.getPrototypeOf(function () {}), Function.prototype);
assert.equal(Object.getPrototypeOf([]), Array.prototype);
assert.equal(Object.getPrototypeOf({}), Object.prototype);var getPrototypeOf = require('object.getprototypeof');
var assert = require('assert');
/* when Object.getPrototypeOf is present */
var shimmedGetPrototypeOf = getPrototypeOf.shim();
assert.equal(shimmedGetPrototypeOf, Object.getPrototypeOf);
assert.equal(Object.getPrototypeOf([]), Array.prototype);Tests
Simply clone the repo, npm install, and run npm test