Importing mml-svg.js into EPUB3 content doc prevents Apple Books pagination

[Christian Roth]

Hello,

as soon as I import mml-svg.js (any version, tried 3.x and latest 4.0 beta) of MathJax into an EPUB3 content XHTML document, Apple Books refuses to paginate that document. There need not be a MathML formula in that page at all, merely adding the script prevents the pagination.

Has anyone run into this as well, is there a solution? 

Details:

I downloaded the MathJax-4.0.0-beta.4 .

I added mml-svg.ja to the EPUB under /js/, and added the following line to the OPF manifest:

    <item id="script1" href="js/mml-svg.js" media-type="text/javascript" />

I added the "scripted" and "mathml" properties to the content document in the manifest:

    <item id="chapter-1" href="chapter-1.xhtml" media-type="application/xhtml+xml" properties="scripted mathml" />

In the content document "chapter-1.xhtml", I include the mml-svg.js like this:

<script src="js/mml-svg.js"></script>

The content document does not contain any MathML – still, Apple Books (Version 6.2 (6030) on macOS) does not paginate the content document - it only displays the first "page", and also does not show its usual "1/x" page position info.

In the Console, the nearest possibly relevant line I can find is:

fault 16:51:45.363090+0100 Books com.apple.iBooks multi-js evaluation failure - Error Domain=WKErrorDomain Code=4 "A JavaScript exception occurred" UserInfo={WKJavaScriptExceptionLineNumber=2, WKJavaScriptExceptionMessage=TypeError: null is not an object (evaluating 't.cssValueType'), WKJavaScriptExceptionColumnNumber=5644, WKJavaScriptExceptionSourceURL=ibooks-script:content_support.js, NSLocalizedDescription=A JavaScript exception occurred}

which looks like there is occurring some exception during processing of the content the content document, but I am not sure if this might be related to the MathJax library.

I am attaching the EPUB I used for testing. It does not paginate for me as attached. It does paginate in Apple Books when I comment out the <script src="js/mml-svg.js"></script> line from the content document.

What could be the issue?

Thanks so much,

Christian

[Davide Cervone]

The error message you provide indicates that the problem is coming from iBooks-script:content_support.js and that it is trying to take the cssValueType from a null object.  This is a file provided by Apple, so is outside of our control.  You may need to report the bug to them.

This page

https://developer.mozilla.org/en-US/docs/Web/API/CSSValue/cssValueType

indicates that the cssValueType is deprecated and may not be supported in most browsers.  For example, it is not available in Firefox.  When I open your pub file in Apple Books v4.4, and older version that you are using, it paginates fine.  So I suspect that somewhere between Books 4.4 and 6.2, the support for the infrastructure for cssValueType has changed, and Apple didn't update their content_support.js file to accommodate that.

Since this value is used to analyze CSS rules, it appears that content_support.js is scanning the stylesheets on the page, and since MathJax does insert stylesheets for its use, that may be what is tripping up content_support.js.

Have you considered pre-processing the xhtml pages rather than running MathJax in them directly?  You could use a program like tex2svg-page from the MathJax-demos-node repository, say the one at

https://github.com/mathjax/MathJax-demos-node/tree/master/component

to pre-process the pages.  Then you won't have to worry about including MathJax at all.  Perhaps that will work better for you.

Davide

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<MathJax import prevents page turning.epub>

[Christian Roth]

Thank you Davide.

I hadn't considered the pre-processing route as I really wanted to make it work as described. But as it turns out, that won't work reliably across the various EPUB reader implementation, so yes, then the pre-processing will be my next try.

I have reported the issue against Apple Books (Apple Feedback Assistant ID: FB13659136, Subject "Apple Books fails to paginate EPUBs (when MathJax is imported)"), but I'm not really hoping for much :-/ 

Thank you,

Christian