There is more than one way to highlight code. hljs.initHighlightingOnLoad() just binds the highlighting operation to the document loading event.

hljs.initHighlightingOnLoad()Code:

function h(){addEventListener("DOMContentLoaded",_,!1),addEventListener("load",_,!1)}

You can see the official documentation of HLJS:
https://highlightjs.org/usage/

There is a code example in the Custom Initialization section:
Example 1:

$(document).ready(function() {
    $('pre code').each(function(i, block) {
        hljs.highlightBlock(block);
    });
});

Example 2

hljs.configure({useBR: true});

$('p.code').each(function(i, block) {
    hljs.highlightBlock(block);
});

So, if you only need to highlight a single area, just

hljs.configure({ ... });
hljs.highlightBlock($('....'));

Language-related configuration is configured through .configure. For configuration items, please refer to: http://highlightjs.readthedoc...