How to convert Katex to latex or mathml?

[arth17singh]

How do I convert katex to latex or mathml? while scrapping a website I have to convert the katex used to mathml or latex so that it can be displayed in ms word files. Any help on this issue will be appreciated.

[mbourne]

@arth17singh Any KaTeX output contains (1) MathML and (2) the original LaTeX, so you can get both.

Here's some typical KaTeX output:

   <span class="katex-mathml">
      <math>
         <semantics>
            <mrow>
             ...
            </mrow>
            <annotation encoding="application/x-tex">
              \displaystyle{b}_{n} = \frac{1}{L}{\int_{-{L}}^{L}} f{{\left({t}\right)}}\  \sin{{\left.\frac{{{n}\pi{t}}}{L}\right.}}{\left.{d}{t}\right.}
            </annotation>
         </semantics>
      </math>
   </span>
   <span class="katex-html" aria-hidden="true">
     ...
   </span>
  </span>

The MathML is contained in the span with class "katex-mathml" and the original LaTeX is in the <annotation> node, with encoding "application/x-tex".

You could extract either of them with javascript.

Hope it helps
Regards
Murray

[arth17singh]

I tried looking into this but couldn't find any katex-mathml class or annotation node on the website html.
<span class="katex"><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1.217331em;vertical-align:-0.345em;"></span><span class="mord"><span class="mopen nulldelimiter"></span><span class="mfrac"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.872331em;"><span style="top:-2.6550000000000002em;"><span class="pstrut" style="height:3em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mtight">3</span></span></span></span><span style="top:-3.23em;"><span class="pstrut" style="height:3em;"></span><span class="frac-line" style="border-bottom-width:0.04em;"></span></span><span style="top:-3.394em;"><span class="pstrut" style="height:3em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mtight">2</span><span class="mord mathnormal mtight" style="margin-right:0.00773em;">R</span></span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.345em;"><span></span></span></span></span></span><span class="mclose nulldelimiter"></span></span></span></span></span>

[arth17singh]

is there some way in which we can take this katex-html and convert it back to the latex or math-ml if these elements are missing?
Thanks

[edemaine]

It looks like the site has disabled the MathML content produced by default by KaTeX (either by setting an option, or by filtering it out afterward). I don't think there's much you can do in this case. (With substantial effort, you could try to reconstruct an approximation of similar LaTeX source, but it's never going to be perfect, and I don't think there's anything easy.)

[arth17singh]

Thanks