first-key.js 349 Bytes
'use strict';

module.exports = function (t, a) {
	var x = {}, y = Object.create(null);
	a(t(x), null, "Normal: Empty");
	a(t(y), null, "Null extension: Empty");
	x.foo = 'raz';
	x.bar = 343;
	a(['foo', 'bar'].indexOf(t(x)) !== -1, true, "Normal");
	y.elo = 'foo';
	y.mar = 'wew';
	a(['elo', 'mar'].indexOf(t(y)) !== -1, true, "Null extension");
};