Backslashes interpreted as control character in JavaScript

Question

I've got LaTex code from server and have no control over it. I would like to print the LaTex code as it is using JavaScript, but it interprets as control characters on assigning to variable.

var str = '\[\frac{{{d^2}y}}{{d{x^2}}} - \,3\,\left( {\frac{{dy}}{{dx}}} \right)\, + \,2y\, = \,0\]';

This interprets as follows

[rac{{{d^2}y}}{{d{x^2}}} - ,3,left( {rac{{dy}}{{dx}}} ight), + ,2y, = ,0]

And I want as follows:

\[\frac{{{d^2}y}}{{d{x^2}}} - \,3\,\left( {\frac{{dy}}{{dx}}} \right)\, + \,2y\, = \,0\]

I tried varies RegExps, and result of

var index = str.indexOf("\\")

is -1

JavaScript removes control characters like \f, \r and so on and there are thousands of backslash notations in TeX.

Answer 1

How is loaded in str var?

Anyway, there is a work around (working here):

var c=',[]flr';
for(var i=0;i<c.length;i++)
 eval("str=str.replace(/\\"+c.charAt(i)+"/g,'\\\\"+c.charAt(i)+"');");

What we do is for any char in c evaluate the following code (replacing X with the char):

str=str.replace(/\X/g,'\\X');

Anyway, there is a work around (working here):

var c=',[]flr';
for(var i=0;i<c.length;i++)
 eval("str=str.replace(/\\"+c.charAt(i)+"/g,'\\\\"+c.charAt(i)+"');");

What we do is for any char in c evaluate the following code (replacing X with the char):

str=str.replace(/\X/g,'\\X');

---

Ok, that's an odd (and maybe dangerous) bug at the site which delivers the JSON. If it does not turns the \' to \', maybe it does not turns the ' to \'. So, anything after a ' or a " (depending on how the string is quoted) will be executed on any site that includes that (i.e. your site). Maybe as JSON is a little more secure.