How do I do strikethrough (line-through) in asciidoc?

That technology is [line-through]#crap# not perfect.

As per Ascii Doc manual, [line-through] is deprecated. You can test here.

Comment from Dan Allen

It's important to understand that line-through is just a CSS role. Therefore, it needs support from the stylesheet in order to appear as though it is working.

If I run the following through Asciidoctor (or Asciidoctor.js):

[.line-through]#strike#

I get:

<span class="line-through">strike</span>

The default stylesheet has a rule for this:

.line-through{text-decoration:line-through}

You would need to do the same.

It is possible to customize the HTML that is generated using custom templates (Asciidoctor.js supports Jade templates). In that case, you'd override the template for inline_quoted, check for the line-through role and produce either an <s> or, preferably, a <del> instead of the span.