Spec bug: Arbitrary CSS classes from fenced code blocks

[walle]

This thread gives a pretty good solution.

@mathias

This means that

var x = 42;

Will not be translated to:

<pre class=“javascript”><code>var x = 42;</code></pre>

…anymore, but instead to:

<pre><code class=“language-javascript”>var x = 42;</code></pre>

Reason: this matches the convention set out in the HTML standard itself — look for the code example that looks something like this:

<pre><code class=“language-javascript”>
…
</code></pre>

If that is not convincing enough, note that this convention is supported by many syntax highlighting scripts written in JavaScript, e.g. highlight.js and google-code-prettify. Requiring Markdown implementations to output code that is recognized by these scripts is a major win.