When I use a code block written in Markdown format, it will be converted into HTML code and wrapped using <pre><code>
markup. No line numbering by default. It’s just a plain view code block. So, I used this vanilla JavaScript code to enable the line numbering in my code block and a little SCSS for the styling.
(function() {
var pre = document.getElementsByTagName('pre'),
pl = pre.length;
for (var i = 0; i < pl; i++) {
pre[i].innerHTML = '<span class="line-number"></span>' + pre[i].innerHTML + '<span class="cl"></span>';
var num = pre[i].innerHTML.split(/\n/).length;
for (var j = 0; j < (num - 1); j++) {
var line_num = pre[i].getElementsByTagName('span')[0];
line_num.innerHTML += '<span>' + (j + 1) + '</span>';
}
}
})();
Here’s my SCSS code:
pre {
display: block;
margin-top: 0;
margin-bottom: 1rem;
line-height: 1.4;
white-space: pre;
overflow: auto;
padding: .5rem 2rem .5rem .5rem;
max-height: 800px;
font-size: .9rem;
code {
display: block;
padding: 0;
}
.line-number {
display: block;
float: left;
margin: 0 1em 0 -1em;
user-select: none; /* Standard */
text-align: right;
span {
display: block;
padding: 0 .5em 0 1em;
}
}
.cl {
display: block;
clear: both;
}
}