Over the summer, we’ve been busy putting together version 2.1 of MathJax. Today we are entering the public beta phase of MathJax v2.1. This release includes a number of small enhancements and over 60 bug fixes. It is available at cdn.mathjax.org/mathjax/2.1-beta/MathJax.js which you can load in place of the version you are currently using.  Alternatively, you can get a ZIP archive to use locally or you can check out the v2.1-latest branch of MathJax by using the commands

git clone git://github.com/mathjax/MathJax.git MathJax-2.1
cd MathJax-2.1
git checkout v2.1-latest`

at an appropriate location on your server.

Remember that this is still beta software, so if you are not an experienced user, you may want to wait for the official 2.1 release.  We do not recommend that you use the 2.1-beta version for production environments, but do encourage you to test your sites with it.

If you’re linking to http://cdn.mathjax.org/mathjax/latest/MathJax.js, note that at the point of the official release of v2.1, the address will begin to serve MathJax v2.1. You can also continue to use v2.0 by linking to http://cdn.mathjax.org/mathjax/2.0-latest/MathJax.js instead – and you can change to that version at any point (it is available now). Once the official v2.1 release is made, the v2.1-beta address will be removed from the CDN.

The official release of v2.1 should occur within the next two weeks, but we wanted you to be able to start to test out the v2.1 features now.  Please report any bugs you find to the issue tracker at https://github.com/mathjax/MathJax/issues.

Thanks for your continuing interest in MathJax.  We hope that this release makes your MathJax experience even smoother.

The MathJax Team.

New in MathJax v2.1

MathJax v2.1 is primarily a bug-fix release. Numerous display bugs, line-breaking problems, and interface issues have been resolved. The complete details are available on the MathJax GitHub issue tracker https://github.com/mathjax/MathJax/issues. The following lists indicate the majority of the bugs that have been fixed for this release.


  • Make NativeMML output properly handle iOS double-tap-and-hold, and issue warning message when switching to NativeMML output.
  • Use scrollIntoView to handle positionToHash rather than setting the document location to prevent pages from refreshing after MathJax finishes processing the math.
  • Handle positioning to a hash URL when the link is to an element within SVG output.
  • Make href’s work in SVG mode in all browsers.
  • Fix problem with opening the “Show Math As” window in WebKit (affected Chrome 18, and Safari 5.1.7).
  • Use MathJax message area rather than window status line for maction with actiontype='statusline' to avoid security restrictions in some browsers.
  • Fix issue where zoom box for math that has been wrapped to the beginning of a line would be positioned at the end of the previous line.
  • Fix a problem where IE would try to typeset the page before it was completely available, causing it to not typeset all the math on the page (or in some cases any of the math).
  • Allow decimal scale values in the dialog for setting the scale.
  • Fix SVG output so that setting the scale will rescale the existing mathematics.
  • Add close button to About box and don’t make clicking box close it (only clicking button).
  • Make About box show ‘woff or otf’ when otf fonts are used (since both are requested).
  • Have output jax properly skip math when the input jax has had an internal failure and so didn’t produce any element jax.
  • Produce MathJax.Hub signal when [Math Processing Error] is generated.


  • Fix problem with SVG output disappearing during line breaks when equation numbers are also present.
  • Fix problem with potential infinite loop when an <mspace> is an embellished operator that causes a linebreak to occur.
  • Allow line breaks within the base of <msubsup> to work so that the super and subscripts stay with the last line of the base.
  • Fix <mfenced> so that when it contains a line break the delimiters and separators are not lost.
  • Allow line breaks at delimiters and separators in <mfenced> elements.
  • Fix issue with line breaking where some lines were going over the maximum width.
  • Fix problem with line breaking inside <semantics>elements.
  • Fix problem with line breaking where the incorrect width was being used to determine breakpoint penalties, so some long lines were not being broken.

HTML-CSS/SVG display:

  • Fix several Chrome alignment and sizing issues, including problems with horizontal lines at the tops of roots, fraction bars being too long, etc.
  • Resolve a problem with how much space is reserved for math equations when a minimum font size is set in the browser.
  • Force final math span to be remeasured so that we are sure the container is the right size.
  • Fix alignment problem in <msubsup>.
  • Fix processing error when rowalign has a bad value.
  • Fix a vertical placement problem with stretched elements in mtables in HTML-CSS, and improve performance for placing the extension characters.
  • Handle spacing for U+2061 (function apply) better.
  • Better handling of primes and other pseudo scripts in HTML-CSS and SVG output.
  • Fixed a problem with <mmultiscripts> in SVG mode that caused processing error messages.
  • Fix misplaced \vec arrows in Opera and IE.
  • Make <mi> with more than one letter have texClass OP rather than ORD in certain cases so it will space as a function.
  • Make HTML snippet handler accept a string as contents, even if not enclosed in braces.
  • Fix spacing for functions that have powers (e.g., \sin^2 x).
  • Fix problem with SVG handling of \liminf and \limsup where the second half of the function name was dropped.
  • Fixed a problem where HTML-CSS and SVG output could leave partial equations in the DOM when the equation processing was interrupted to load a file.
  • Fix problems with <mtable>, <ms>, and <mmultiscripts> which weren’t handling styles.
  • Make column widths and row heights take minsize into account in <mtable>.
  • Fix typo in handle-floats.js that caused it to not compile.
  • Fix problem in HTML-CSS output with <msubsup> when super- or subscript has explicit style.

TeX emulation:

  • Allow negative dimensions for \\[] but clip to 0 since this isn’t really allowed in MathML.
  • Fixed problem where \\ with whitespace followed by [ would incorrectly be interpretted as \\[dimen].
  • Make jsMath2jax run before other preprocessors so that tex2jax won’t grab environments from inside the jsMath spans and divs before jsMath2jax sees them.
  • Fix issue with \vec not producing the correct character for \vec{\mathbf{B}} and similar constructs.
  • Combine multiple primes into single unicode characters.
  • Updated the unicode characters used for some accents and a few other characters to more appropriate choices. See issues #116, #119, and #216 in the MathJax issue tracker on GitHub.
  • Remove unwanted 'em' from eqnarray columnwidth values.
  • Make eqnarray do equation numbering when numbering is enabled.
  • Make vertical stretchy characters stand on the baseline, and improve spacing of some stretchy chars.
  • Make mtextFontInherit use the style and weight indicated in the math, so that \textbf and \textit will work properly.
  • Add \textcolor macro to the color extension.
  • Added RGB color model to the color extension.
  • Automatically load the AMSmath extension when needed by the mhchem extension.
  • Add <<=> arrow to mhchecm extension
  • Fix alignment of prescripts in mhchem to properly right-justify the scripts.
  • Expose the CE object in the mhchem extension.
  • Make autoload-all skip extensions that are already loaded, and not redefine user-defined macros.
  • Fix most extensions to not overwrite user defined macros when the extension is loaded.
  • Ignore \label{} with no label.
  • Make \injlim and friends produce single <mi> elements for thier names rather than one for each letter.
  • Handle primes followed by superscript as real TeX does in TeX input jax.
  • Handle a few more negations (e.g., of arrows) to produce the proper Unicode points for these.
  • Don’t produce a processing error when \limits is used without a preceding operator.

MathML Handling:

  • Prevent align attribute on <mtable> from applying to <mover>/<munder>/<munderover> elements.
  • Ignore _moz-math-* attributes in MathML input so they don’t appear in MathML output
  • Prevent duplicate xmlns attributes in “Show Math As -> MathML”.
  • Fixed a problem in MathML output where dimensions given to <mpadded> with leading +’s could lose the plus and become absolute rather than relative.
  • Fix setTeXclass for TeXatom so that it handles the spacing for relations correctly.
  • Add more CSS to isolate NativeMML output from page.
  • Handle setup of MathPlayer better for IE10, and avoid some IE10 bugs in setting the document namespace for MathML.


  • Fix a problem where bold-script didn’t work properly in STIX fonts.
  • Work around Chrome bug with MathJax web fonts that affects some combining characters.
  • Remove dependencies of TeX->MathML conversion on the choice of fonts (TeX versus STIX).
  • For stretchy characters that don’t have a single-character version in the MathJax fonts, make sure they are properly sized when not stretched or stretched to a small size.
  • Fix an error with U+u005E (^) which caused it to show as a plus when used as a stretchy accent.
  • Fix a problem with greek letters in STIX font producing the wrong letter (an offset was off by one).
  • Handle more characters in sans-serif-italic and bold-italic STIX fonts.