Check if string contains character not on list
<p>For example, I have an approved list of characters: "a", "b", and "c".</p>

<p>So if I had the string:</p>

<pre><code>var string = "aaabc8abccc";
</code></pre>

<p>I would like the script to detect the fact that the "8" is not "a", "b", or "c" and output:</p>

<pre><code>var output = "aaabc&lt;span style='color:red;'&gt;8&lt;/span&gt;abccc";
</code></pre>

<p>How can I do this?</p>
