How to label equations on the left with mathjax?

Question

In a proper TeX environment, one can use preamble to set the equation labels (tags) on the left for the entire document. There are also tricks to do this locally.

On the webpage here, sometimes a tag on the right end seems too far. (I'm a two-column person)

Is it possible in Math StackExchange (using mathjax or alternatives) to label text or equations on the left, at the beginning of a line?

The point is that the labels should properly work as hyperlinks, jumping to the place you want to show. That is, lists or itemize is no good for this purpose.

Another motivation for this is that: if such method exists, it can also be useful as a work-around for section/paragraph labeling within a single post, which I gather is not possible with mathjax.

I tried to require the TeX hyperref or similar packages, but so far I cannot figure out the correct syntax. I also considered phantom-like labels like \tag*{$\color{white}{__some text__}$} to push the label around. Of course this doesn't work.

I don't know any java and I have limited skills in html, but I'm open to anything that works on this site (and isn't disruptive to the system).

---

P.S.

I'm not talking about left-aligning an equation like what this post addresses. However, if this can be made into a left-tag trick, I'd love to know.

Answer 1

${\def\Target#1{\rlap{\smash{\label{#1}\phantom{\tag{#1}}}}}}$$\Target{Start}$This is possible, if inconvenient. This answer demonstrates how it can be done.

$\Target{Instructions}$In short:

1. Started the post with a helper function for defining labels.

   ${\def\Target#1{\rlap{\smash{\label{#1}\phantom{\tag{#1}}}}}}$

2. Defined label-points by either:

   • adding \Target{name} into existing equations, or

   • adding a zero-width equation, $\Target{name}$.

3. Link the label-points as:

   https://math.meta.stackexchange.com/questions/28149/how-to-label-equations-on-the-left-with-mathjax#mjx-eqn-LabelName.

For example, this link should target "In short:" above, which is actually written up as

$\Target{Instructions}$In short:

and "this link" is

[this link](https://math.meta.stackexchange.com/questions/28149/how-to-label-equations-on-the-left-with-mathjax#mjx-eqn-Instructions)

.

$$ \left[\text{back to start}\right] $$

Answer 2

I have used \tag{1}\label{1} and then referred to it with \eqref{1} and \ref{1}. The \tag puts the visual cue, while the \label puts the hyper reference.

Answer 3

To copy this from my earlier comment.

Generally speaking, this can be done. However, it's only possible by changing the MathJax configuration (cf. TagSide in the TeX input processor options).

This means, the change has to occur on the page/site level.