We already have logic that should skip over backslashes:

https://github.com/Khan/KaTeX/blob/c79fb5893686ac0b8c4d8ec33ea1b940d2e4a0c4/contrib/auto-render/splitAtDelimiters.js#L16

Maybe it's not working?

That only works for escaping $ inside of math, but not outside of it. @paulsohn can you give an example of what you're trying to do?

Rendering this text:

I will give you \$2 if you can solve $y = x^2$.

with this delimiter:

{ left: '$', right: '$', display: false }

results in

<#text>I will give you \</#text>
<span>KATEX MATH</span>
<#text>y = x^2</#text>
<#text>$.</#text>

where <#text> denotes a text DOM node.

Agreed, can not write dollar sign outside of math equations...

@paulsohn can you use different delimiters, e.g. \(,\) and \[,\]?

I'm going to close this since it's going to be very difficult to implement something that handles the different behaviors people want. Also, there is a workaround by using different delimiters.

Just a question, How can I make the following string be ignored by katex?

John bought a shirt, a pair of pants, and a pair of shoes, which cost $10, $20, and $30, respectively. What percent of the total expense was spent for the pants?

It is being rendered like this:

There is more than one way to do this. If you are using the KaTeX auto-render extension, then you can delimit your math with \(…\) instead of $…$. Or you can nest the whole phrase in <noscript>…</noscript> tags.

Some markdown parsers only recognize the closing $ as a math delimiter if it is not followed by a number. Sometimes I think we should do that too.

Thanks for replying. I simply replaced my $ with <span>$</span> and this made Katex ignore it. I'm putting it out so that someone else also tries it if they're stuck.

Would be nice for MathJax processEscapes compatibility: http://docs.mathjax.org/en/latest/options/preprocessors/tex2jax.html#configure-tex2jax

@Trass3r can you open a new issue for processEscapes?

Isn't it exactly this issue?

When set to true, you may use \$ to represent a literal dollar sign. Typically this is set to true if you enable the $ ... $ in-line delimiter

I'm re-opening and have changed the title to indicate that we'd like an option to ignore \$.

To have \$ render as a normal $ and not as the beginning of inline latex I added one line of javascript that replaces \$ with <span>$</span>.

<script>
    document.addEventListener("DOMContentLoaded", function() {
        // https://sixthform.info/katex/guide.html
        document.body.innerHTML = document.body.innerHTML.replace(/\\\$/g, '<span>$</span>');
	
        renderMathInElement(document.body, {
           // ... https://katex.org/docs/autorender.html
        });
        
    });
</script>

I have made a pull request that changes the autorender in the following way:

If a left delimiter is preceded by a backslash (\), the backslash is stripped and the delimiter is ignored (math mode is not entered). So \$40 is greater than \$30 gets transformed to $40 is greater than $30, if $ is configured to be a starting delimiter. If it is not, the backslashes are left untouched.

I think this is safe and sane enough behavior to have as a default. The only way existing users are affected by this is if they have a backslash immediately (no whitespace or anything) followed by a delimiter that enters math mode. I can't think of any scenario where one would want that, and if one still does one can do \<span></span>$ or \$ (or a variety of other methods, zero-width spaces, etc).

This also means that \\( becomes just a literal \( and such - it is not limited to $.