Support \eqref and \label

Before requesting a feature, please search for existing issues.

Is your feature request related to a problem? Please describe. I am trying to migrate from Mathjax to Katex, however, \eqref and \label are not supported for the moment. Any roadmap on this?

Describe the solution you’d like: Support \eqref and \lable for equation reference

Link to or name of a (La)TeX package that provides the same feature: KaTeX’s general goal is to render as LaTeX does.

Describe alternatives you’ve considered: A clear and concise description of any alternative solutions or features you’ve considered.

Additional context: Add any other context or screenshots about the feature request here.

[zhangpeng96]

Inspired by this issue: https://github.com/falgon/roki-web/issues/34 We can use KaTeX’s marco command to implement \eqref & \label function by \href & \htmlId command

ATTENTION: \href & \htmlId command are disabled by default, we must add them into trust option

UPDATE: The previous trust setting code is wrong, as @nschloe said, trust only accept boolean or function. We can use function type to allow specific commands. Thank nschloe very much!

KaTeX option:

trust: (context) => ['\\htmlId', '\\href'].includes(context.command),
macros: {
  "\\eqref": "\\href{###1}{(\\text{#1})}",
  "\\ref": "\\href{###1}{\\text{#1}}",
  "\\label": "\\htmlId{#1}{}"
}

example:

Search by definition $\eqref{1-1}$ or $\ref{1-1}$.

$$
\begin{aligned} \sin 2\theta = 2\sin \theta \cos \theta \\ = \cfrac{2 \tan \theta}{1+\tan^2 \theta} \end{aligned} \label{1-1}\tag{1-1}
$$

Used in the same way as LaTeX or MathJax.

[edemaine]

@kevinbarabash Neat idea. One challenge is that labels and refs will generally span multiple equations, so this would need to be done at the autorender level. But maybe if we work out the interface for how autorender could do it, we could get a more general API…