Check if Katex macro persistence can work

[laurent22]

https://discourse.joplin.cozic.net/t/is-there-a-way-to-get-katex-global-macros-working/1316

[eddiemundo]

I think the problem is that some object needs to be passed to katex.renderToString as the macro option every time katex.renderToString is called. Mentioned in https://katex.org/docs/options.html, under macros: object it says:

This object will be modified if the LaTeX code defines its own macros via \gdef, which enables consecutive calls to KaTeX to share state.

So I think these changes are needed to make \gdef work (I haven't tested them):

class MdToHtml_Katex {

	constructor() {
		this.cache_ = {};
		this.assetsLoaded_ = false;
                // initial empty macro object
                this.macros = {};
	}

       // ...

	processContent(renderedTokens, content, tagType) {
		try {
			const cacheKey = tagType + '_' + content;
			let renderered = null;

			if (this.cache_[cacheKey]) {
				renderered = this.cache_[cacheKey];
			} else {
				renderered = katex.renderToString(content, {
					displayMode: tagType === 'block',
                                        // here we put the (mutatable) macro object
                                        macros: this.macros
				});
				this.cache_[cacheKey] = renderered;
			}

			if (tagType === 'block') renderered = '<p>' + renderered + '</p>';

			renderedTokens.push(renderered);
		} catch (error) {
			renderedTokens.push('Cannot render Katex content: ' + error.message);
		}
		return renderedTokens;
	}

        // ...
}

[laurent22]

I've tried the two examples on the forum but for both the app says that it's invalid Katex code.

$$
\gdef\matrix#1{\begin{bmatrix}#1\end{bmatrix}}
$$
$$
\matrix{1&2&4\1&2&3}
$$

$$
\gdef\matrix#1{\begin{bmatrix}#1\end{bmatrix}}
\matrix{1&2&4\1&2&3}
$$

Any chance you could post examples that work and expected result?

[eddiemundo]

Yes sorry I didn't use code blocks so a backslash got eaten.

The below should display a matrix but doesn't. It has a "global macro" defined in the first pair of $$, and this macro should be able to be used in the second pair of $$.

$$
\gdef\matrix#1{\begin{bmatrix}#1\end{bmatrix}}
$$
$$
\matrix{1&2&4\\1&2&3}
$$

The below does display a matrix, but because the usage of the defined macro is in the same $$ pair.

$$
\gdef\matrix#1{\begin{bmatrix}#1\end{bmatrix}}
\matrix{1&2&4\\1&2&3}
$$

[laurent22]

The solution you posted above worked.