How do I return an array of elements NOT in a Javascript map?
<p>I have a Javascript object:</p>

<pre><code>var errorMap = {
    100: 'You must enter a name.',
    200: 'You must enter an address.',
    300: 'You must enter a DOB.'
}
</code></pre>

<p>In another part of my code, I am receiving an array of error codes:</p>

<pre><code>var errorCodes = [100, 200, 500, 600];
</code></pre>

<p>What I'd like to do is compare the <code>errorCodes</code> array to the <code>errorMap</code> object's keys and return all error codes that do <strong>not</strong> have a corresponding key in <code>errorMap</code>. In this case, I would like to get this back:</p>

<pre><code>[500, 600]
</code></pre>

<p>How do I do this? I have access to jQuery.</p>
