has-property-descriptors 
Does the environment have full property descriptor support? Handles IE 8's broken defineProperty/gOPD.
Example
var hasPropertyDescriptors = require('has-property-descriptors');
var assert = require('assert');
assert.equal(hasPropertyDescriptors(), true); // will be `false` in IE 6-8, and ES5 engines
// Arrays can not have their length `[[Defined]]` in some engines
assert.equal(hasPropertyDescriptors.hasArrayLengthDefineBug(), false); // will be `true` in Firefox 4-22, and node v0.6
Tests
Simply clone the repo, npm install
, and run npm test