Cannot get MathJax-node to work in Windows

[sammarshallou]

I successfully got the npm install to work in Windows 7 (which was a nightmare and a half already), but the MathJax-node binaries don't work for me. Using mingw bash (also tested with windows command prompt just in case that helped, but it has the same result).

I run:

$ bin/tex2svg 'x_2'

The result is nothing - i.e. it pauses for about 1-2 seconds then exits and shows the $ prompt again, with no output.

Originally I was using node.js v0.10.something. I've since updated to the latest v0.12.0 (and did a rebuild and update) but with same result.

I tried adding console.log calls in various places in the script (bin/tex2svg). As a result I can confirm that it runs the script from start to finish, but does not run the callback that is supposed to happen when typesetting finishes.

I also have a Linux VM where I also installed MathJax-node the same way and this does work fine, returning SVG code.

Basically wondering if this is just my setup, or if it's known to not work in Windows for some reason. Our production servers are Linux but for development it is sometimes convenient if we can run stuff on Windows also.

[pkra]

Thanks for the report. I don't think we've had anyone test MathJax-node on Windows.

Given that you've gone through it, do you have any advice on pitfalls during installation?

[sammarshallou]

Thanks! OK, I was wondering whether anybody else had tried it. Seems a bit strange that there's no error message (that I can see). It's entirely possible that this is just something wrong with my system somehow but maybe somebody else will comment if it's a shared issue.

The installation difficulty I had isn't mathjax-node's problem - it's really just because mathjax uses the node.js jsdom module, specifically I think it's 'contextify' which is a dependency of that which causes the difficulty because it is a native code thing that is compiled using the 'gyp' module.

Basically in order to get the 'npm install' command to work in my Windows 7 (64-bit) I had to to:

1. Install node.js (well, actually I had this already)
2. Install Python 2.7 (apparently later versions won't work)
3. Install MS Visual Studio 2012 Express (that's the name of the free version; ironically, this install took approximately 5 hours).
4. Set the environment variable GYP_MSVS_VERSION to 2012

After that, npm install worked. The hard part was finding the environment variable because it's not really documented that I saw, I eventually got it from somebody else's slightly different problem in a google search - the rest is covered in https://github.com/TooTallNate/node-gyp

[pkra]

Thanks for the additional information. I got mathjax-node running (though I didn't need step 4) and could reproduce this -- but ran out of time. Will try to find some more time later this week.

[dpvc]

I was trying out jsdom 3.1.1, and it failed in the same way you describe, and tracked it down to the handling of the MathJax URL, which is a file:// URL. It looks like the url.resolve() method in node doesn't handle some URL's correctly, and Windows URL's with disks appear to be one of them. Try editing lib/mj-single.js and find the line that sets MathJaxPath. Change the "file://" to just "file:" (no slashes) and see if that helps. If not, add

console.error(MathJaxPath);

right after that line and see what the path actually is and let us know. I think it is probably that jsdom isn't able to locate MathJax.js properly.

[sammarshallou]

Thanks for looking into this! That didn't solve it but you're right about this being an error. After your change the path was:

file:c:\users\sm449\workspace\MathJax-Node\node_modules\MathJax\unpacked\MathJax.js

Which still doesn't work. After various experimentation I found a change that does work (after the original code):

if (/^file:\/\/[A-Za-z]:\\/.test(MathJaxPath)) {
    MathJaxPath = MathJaxPath.replace(/\\/g, '/');
    MathJaxPath = MathJaxPath.replace(/^file:\/\/(.):\//, 'file:///$1:/');
}

This makes it use the URL that Firefox accepts, which is file:///c:/whatever/etc

Not sure if this is the best way to solve the problem (I'm not at all familiar with node.js) but if you want to use that change, it's this commit:

sammarshallou@30cc46a

(Feel free to do it differently in your own commit obviously. :) Or if you want me to submit it using the pull request thingy, I can.)

[dpvc]

Thanks for checking that out and finding a solution. Can you do one more thing for me? Can you run

node -e 'console.log(require("jsdom").jsdom().URL)'

on the command line and tell me what the output is?

[sammarshallou]

Sure. It is:

file:///c:/users/sm449/workspace/MathJax-Node/[eval]

[dpvc]

OK, thanks. Now how about

node -e 'console.log(require("url").resolve("file:///c:/blank.html","file:c:/users/sm449/test.html"))'

Hate to keep making you do this, but I haven't set up MathJax-node on Windows yet myself (though I will probably have to).

[sammarshallou]

I'm happy to do this (so long as you don't mind waiting if I'm not at my desk or don't notice it for an hour or something). :) Actually pretty glad to get it working in Windows at all now as that's going to make my life easier, so thanks.

Result to that one is a bit weird:
file:///c:/c:/users/sm449/test.html

[dpvc]

If you are willing to keep trying, here is another couple:

node -e 'console.log(require("url").resolve("about:blank","file:c:\\users\\sm449\\test.html"))'
node -e 'console.log(require("url").resolve("about:blank","file://c:\\users\\sm449\\test.html"))'
node -e 'console.log(require("url").resolve("about:blank","file:///c:\\users\\sm449\\test.html"))'
node -e 'console.log(require("url").resolve("file:///blank.html","file:c:\\users\\sm449\\test.html"))'
node -e 'console.log(require("url").resolve("file:///blank.html","file://c:\\users\\sm449\\test.html"))'
node -e 'console.log(require("url").resolve("file:///blank.html","file:///c:\\users\\sm449\\test.html"))'

[dpvc]

PS, I'm going to be away from my computer for the rest of the day starting in about an hour, so we may not get this resolved today.

I'm glad you were able to get it to work for you on Windows, and that you are able to work more efficiently there.