Add mhchem support to rehype-katex #81

MrWillCom · 2023-02-17T15:05:39Z

Initial checklist

I read the support docs
I read the contributing guide
I agree to follow the code of conduct
I searched issues and couldn’t find anything (or linked relevant results below)

Problem

I'm using LaTeX to write some docs about Chemistry, and I need mhchem to write equations easily.

Solution

However, rehype-katex is pure, and does not support \ce{} syntax by default. To use mhchem in KaTeX, I need mhchem extension, which is an official extension made by KaTeX team.

Adding <script /> into <head /> directly is not recommended, and doesn't work properly with Next.js built-in router.

Alternatives

Well, switching to rehype-mathjax works, but, #80 happens to me, too.

import { unified } from "unified";
import remarkParse from "remark-parse";
import remarkMath from "remark-math";
import remarkRehype from "remark-rehype";
import rehypeKatex from "rehype-katex";
import rehypeStringify from "rehype-stringify";

import "katex/dist/contrib/mhchem";

const sourceMarkdown = `
$\\ce{a A + b B -> c \\textbf{C} + d D}$
`;

const file = await unified()
  .use(remarkParse)
  .use(remarkMath)
  .use(remarkRehype)
  .use(rehypeKatex)
  .use(rehypeStringify)
  .process(sourceMarkdown);

runnable example: https://codesandbox.io/s/katex-mhchem-wl7q64

MrWillCom · 2023-02-17T16:16:30Z

Thank you so much! Excuse me, but how can I use this with Next.js?

I've tried to add katex/dist/contrib/mhchem with CDN, like this:

import Script from 'next/script'

...

<Script src="https://cdn.jsdelivr.net/npm/katex@0.16.4/dist/contrib/mhchem.min.js" />

However, \ce{} doesn't work and an error is thrown in the console:

Thanks again for your patience, do you have any idea with this?

ChristianMurphy · 2023-02-17T17:12:09Z

Could you share what you are trying to do in a sandbox? Using https://next.new as a starter?
There are a bunch of different integrations with Next for different use cases, it's unclear which you are using.
Also this may be better suited as a Q&A discussion: https://github.com/orgs/remarkjs/discussions

philipbalbas · 2023-02-22T18:32:26Z

Hi, I have a similar issue where I'm importing mhchem to a Nextjs project but the equations aren't rendering correctly.

https://stackblitz.com/edit/nextjs-idj33f?file=pages%2Fmath.js,pages%2Findex.js,pages%2F_app.js

ChristianMurphy · 2023-02-22T22:30:17Z

Thanks @philipbalbas!

Given that https://codesandbox.io/s/katex-mhchem-wl7q64 works in browser
I suspect there is an issue where the plugin isn't able to register in node/next

ChristianMurphy · 2023-02-22T23:02:42Z

Taking that further, I tried to isolate the issue a bit more.
I ended up with https://stackblitz.com/edit/nextjs-xvqkxb?file=pages/index.js
It feels like next is isolating or messing with the katex context, I'm not sure, the next team may be able to offer more commentary on what next is doing. https://github.com/vercel/next.js/discussions

philipbalbas · 2023-02-23T02:03:51Z

Hi, thanks for taking a look. Noted on the nextjs issues.
I also suspect mdxjs not getting the context of mhchem but will have to investigate further.

ChristianMurphy · 2023-02-23T04:18:58Z

I also suspect mdxjs not getting the context of mhchem but will have to investigate further.

That is the side effect, yes.
It doesn't necessarily get at the "why?"
Given https://codesandbox.io/s/katex-mhchem-wl7q64 and https://stackblitz.com/edit/nextjs-xvqkxb?file=pages/index.js clearly rehype-katex clearly can access the mhchem context.
With the smaller reproducible examples it's increasingly looking like it works up to the point next it added to the picture.
Which implies something next is doing is likely the root cause.

Combined with #80 it leads me to believe something about Next SSR messes with Katex and Mathjax.
Remark and MDX just happen to also be in the dependency tree, but seem to be unrelated to the issues being seen.

edward1127 · 2023-08-31T08:29:23Z

I'm getting the same issue to make mhchem work with nextjs. Have anyone solved the issue?

import "katex/dist/katex.min.css";
import "katex/dist/contrib/mhchem";
import rendererStyle from "@/styles/quesiton-renderer.module.scss";
import React, { useMemo } from "react";
import remarkMath from "remark-math";
import remarkGfm from "remark-gfm";
import rehypeKatex from "rehype-katex";
import ReactMarkdown from "react-markdown";
import remarkDirective from "remark-directive";
import rehypeStringify from "rehype-stringify";
import remarkDirectiveRehype from "remark-directive-rehype";
import MathField from "./Control/MathField";
import type { IQuestion } from "@/interfaces/problems";
import TextInput from "./Control/TextInput";
import Checkbox from "./Control/Checkbox";
import TextArea from "./Control/Editor";
import Editor from "./Control/Editor";
import Radio from "./Control/Radio";
import { environment } from "@/lib/environment";
import type { FormValues } from "../Form/ProblemForm";
import SketchCanvas from "./Control/SketchCanvas";
import Matching, { MatchField } from "./Control/Matching";
import CSSInJs from "./CSSInJs";
import { cn } from "@/lib/style";

function QuestionRender({
  question,
  isEditMode = false,
  className,
}: {
  question: Partial<IQuestion> | FormValues;
  isEditMode?: boolean;
  className?: string;
}) {
  const components = useMemo(() => {
    return {
      "math-input": (props: any) => (
        <MathField isEditMode={isEditMode} question={question} {...props} />
      ),
      "text-area": (props: any) => (
        <TextArea isEditMode={isEditMode} question={question} {...props} />
      ),
      "text-input": (props: any) => (
        <TextInput isEditMode={isEditMode} question={question} {...props} />
      ),
      "match-field": (props: any) => (
        <MatchField isEditMode={isEditMode} question={question} {...props} />
      ),
      matching: (props: any) => (
        <Matching isEditMode={isEditMode} question={question} {...props} />
      ),
      canvas: (props: any) => (
        <SketchCanvas isEditMode={isEditMode} question={question} {...props} />
      ),
      editor: (props: any) => (
        <Editor isEditMode={isEditMode} question={question} {...props} />
      ),
      radio: (props: any) => (
        <Radio isEditMode={isEditMode} question={question} {...props} />
      ),
      checkbox: (props: any) => (
        <Checkbox isEditMode={isEditMode} question={question} {...props} />
      ),
      p: (props: any) => <>{props.children}</>,
      img: ({ className, ...props }: { className: string; props: any }) => (
        <img
          className={`w-auto lg:max-w-[50%] max-h-96 ${
            className ? className : ""
          }`}
          {...props}
        />
      ),
      ins: ({ className, ...props }: any) => (
        <span className={cn("underline", props.className)} {...props}>
          {props.children}
        </span>
      ),
      box: (props: any) => (
        <div className={cn("border-2 border-black p-3", props.className)}>
          {props.children}
        </div>
      ),
      blank: ({ className, ...props }: any) => (
        <span
          className={cn("border-b-2 px-5 border-black", className)}
          {...props}
        >
          {props.value || props.children}
        </span>
      ),
      table: ({ className, ...props }: { className: string; props: any }) => (
        <table
          className={`table-fixed my-3 ${className ? className : ""}`}
          {...props}
        />
      ),
      td: ({
        className,
        isHeader,
        ...props
      }: {
        className: string;
        isHeader: boolean;
        props: any;
      }) => {
        return (
          <td
            className={`align-middle ${className ? className : ""}`}
            {...props}
          />
        );
      },
    };
  }, [question]);

  return (
    <>
      <ReactMarkdown
        className={cn(
          `max-w-none dynamic-tailwind prose leading-10 text-black ${rendererStyle["question-render"]}`,
          className
        )}
        remarkPlugins={[
          remarkMath,
          remarkGfm,
          remarkDirective,
          remarkDirectiveRehype,
        ]}
        rehypePlugins={[rehypeKatex, rehypeStringify]}
        components={components}
        transformImageUri={(src, alt, title) => {
          return `${environment.staticUrl}/${src}`;
        }}
      >
        {question.description}
      </ReactMarkdown>
      {isEditMode && <CSSInJs description={question.description} />}
    </>
  );
}

export default React.memo(QuestionRender);

ChristianMurphy · 2023-08-31T17:45:07Z

Welcome @edward1127! 👋
Did you get a chance to read my message right before yours?
In particular:

Combined with #80 it leads me to believe something about Next SSR messes with Katex and Mathjax.
Remark and MDX just happen to also be in the dependency tree, but seem to be unrelated to the issues being seen.

This doesn't appear to be a remark/mdx issue, so there isn't necessarily a remark/mdx workaround to be offered.
It may be a good idea to float this question to the Next.js team (https://github.com/vercel/next.js/discussions), then cross-post the link to the Next.js discussion here so that it can be more easily found by others.

edward1127 · 2023-08-31T18:06:00Z

Thanks. I just reposted your summary to the Next.js team vercel/next.js#54852

edward1127 · 2023-09-01T00:20:37Z

I tried to use CSR with Next https://stackblitz.com/edit/nextjs-ftepsg?file=pages%2Findex.js, and it's still not working. I believe somehow nextjs cannot get the context of import "katex/dist/contrib/mhchem";

edward1127 · 2023-11-22T07:13:30Z

If explicitly import the mhchem extension, it will work for nextjs
#92

github-actions bot added 👋 phase/new Post is being triaged automatically 🤞 phase/open Post is being triaged manually and removed 👋 phase/new Post is being triaged automatically labels Feb 17, 2023

ChristianMurphy closed this as not planned Won't fix, can't repro, duplicate, stale Feb 17, 2023

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ChristianMurphy added the 🙋 no/question This does not need any changes label Feb 17, 2023

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ChristianMurphy mentioned this issue Aug 31, 2023

rehype-mathjax: CHTML not rendering #85

Closed

4 tasks

JounQin mentioned this issue Nov 22, 2023

fixed an issue that nextjs cannot render katex's mhchem extension #92

Closed

5 tasks

wooorm mentioned this issue Apr 10, 2024

mhchem doesn't seem to work with rehype-katex #97

Closed

4 tasks

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Add mhchem support to rehype-katex #81

Add mhchem support to rehype-katex #81

MrWillCom commented Feb 17, 2023 •

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Add mhchem support to rehype-katex #81

Add mhchem support to rehype-katex #81

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MrWillCom commented Feb 17, 2023 • edited Loading

Initial checklist

Problem

Solution

Alternatives

Related

ChristianMurphy commented Feb 17, 2023 • edited Loading

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