title: MathJax Zoom.js issue Shiny
body: <p>I see in 2014 <a href="https://stackoverflow.com/questions/25705703/mathjax-in-shiny-suddenly-stopped-working">others</a> also had the problem that MathJaxzoom.js stopped working in R's Shiny app. It gives the following error:</p>
  
  <pre><code>File failed to load: http://127.0.0.1:4299/file1a9839f31451_files/mathjax-local/extensions/MathZoom.js
  </code></pre>
  
  <p>I now get the same problem - is it still a persistent problem? It worked this morning and just randomly stopped doing so now. </p>
  
  <p>Any ideas on how to fix this or why it failed to work?</p>
  
  <p>Session info:</p>
  
  <pre><code>R version 3.2.3 (2015-12-10)
  RStudio Version 0.99.876
  leaflet_1.0.0        tidyr_0.4.0         
  dplyr_0.4.3          lubridate_1.5.0     RevoUtilsMath_3.2.3
  htmltools_0.3        shiny_0.13.0        plotly 2.0.16
  </code></pre>