#object-keys 
An Object.keys shim. Uses Object.keys if available.
Example
var keys = require('object-keys');
var assert = require('assert');
var obj = {
a: true,
b: true,
c: true
};
assert.equal(keys(obj), ['a', 'b', 'c']);
Source
Implementation taken directly from es5-shim, with modifications, including from lodash.
Tests
Simply clone the repo, npm install, and run npm test