How to customise mkdown render behavior?

I am using highlight.js 9.1.0 for syntax highlighting. The problem is that it only renders the following block:

<pre><code class="language-xxx">


<pre><code class="xxx">

where xxx stands for the name of the language.

As far as I know, hugo uses BlackFriday as markdown render. The later will translate fenced block

lazy val a = 1


lazy val a = 1

, but not

lazy val a = 1
As a result, highlight.js can not find the block with the require class name. The highlight does not work at all.

So how to make md render or hugo to generate the expected html as shown above without changing hugo code and recompiling it ?

For the moment, I workaround with a js file to modify the class name. But I prefer a native way to achieve that.

Any ideas?

Thank you.

From highlight.js:

Classes can also be prefixed with either language- or lang-.

I suspect you have some other problem with hightlight.js initialization.