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How to handle edge case while trying to grab all digits including decimal between two chars using regex

I am parsing a series of strings with various formats. The last edge case encountered has me stumped. I'm not a great regexer, believe me it was a challenge to get to this point.
Here are critical snippets from the strings I'm trying to parse. The second example is the current edge case I'm stuck on.
LBP824NW2-58.07789x43.0-207C72
LBP824WW1-77.6875 in. x 3.00 in. 24VDC
I am trying to grab all of the digits (including the decimal) that make up the width part of the dimension in the string (this would be the first number in the dimension). What works in every other case has been grabbing all digits from the "-" to the "x" using the following expression:
/-(\d+\.?\d+?)x\B/
However, this does not handle the cases that have inches included in the dimension. I thought about using "look-aheads" or "look-behinds", but I got confused. Any suggestions would be appreciated.

RegEx can be told to look for "zero or one" of things, using (...)? syntax, so if your pattern already works but it gets confused by a new pattern that simply has "more string data embedded in what is otherwise the same pattern" you can add in zero-or-one checks and you should be good to go.
In this case, putting something like (\s*in\.?\s*)? in a few tactical places to either match "any number of spaces (including none) followed by in followed by an optional full stop followed by any number of spaces (including none)" or nothing should work.
That said, "I cannot change the formatting" is almost never an argument, because while you can't change the formatting, you can almost always change what parses it. RegEx might be adequate, but some code that checks for what kind of general patter it is, and then calls the appropriate function for tokenizing and inspecting that specific string pattern should be quite possible. Unless you've been hired to literally update some predefined CLi script that has a grep in it and you're not allowed to touch anything except for the pattern...

This is the working solution using regex: -(\d+\.?\d+?)(\s*in\.?\s*|x)

Delimiting documents with regular expressions

I'm working on several documents that are within just a file, and before working on the documents, I need to define where one document begins and ends. For this, I am using the following regex:
MINISTÉRIO\sDO\sTRABALHO\sE\sEMPREGO(?:[^P]*(?:P(?!ÁG\s:\s\d+\/\d+)[^P]*)*)PÁG\s:\s\d+\/(\d+)\b(?:\D*(?:(?!\1\/\1)\d\D*)*)\1\/\1(?:[^Z]*(?:Z(?!6:\s\d+)[^Z]*)*)Z6:\s\d+
Example is here
Is working 100%, the problem is, sometimes the text does not come this way I showed.. it comes with spaces and lines. As you can see here, the document is the same as the previous one, but the regular expression does not work. I wonder why is not working and how to fix to make it work ?
Also, I need modify the regex, not the text, cause the only real part that I have access is the regex.
OBS: I'm using Node.JS, that's why i'm tagging with JS this post.

how to prevent scripts from being run

SO kept preventing me from posting the title I wanted so finally got a title that let me post though it kind of sucks so feel free to edit/change it.
I have fields a user can fill in and in the javascript we have
'${chart.title}'
and stuff like that. Is it sufficient to just strip out the single quote character such that they cannot escape it back to javascript? or are there other ways to close out the string that started with the single quote character.
${chart.title} inserts the title a user typed in on a previous page so naturally they could type something like "Title'+callMethod()+'RestOfTitle" injecting a callMethod into my javascript.
thanks,
Dean

The best way would be to restrict the input to alphanumerical and space characters.
If you want to allow anything inside the title, you can use a escaping function.
http://xkr.us/articles/javascript/encode-compare/
Just stripping the string of single quote characters is definitely not enough. Think of new lines for one reason.

There are couple of options.
First go very restrictive way and do both so called white-list validation for input field for you title and always encode the text that you output to the page. That will filtered out all unwanted (and potentially dangerous) characters and make sure that if some of them pass filter (or somebody update the text to contains some js code after the filters were applied) the encoding procedure make all malicious js scripts not runable (it turns it into plain text).
Second you do let your users input what ever they want (which is highly unrecommended way but sometime developers asked to do it) but always encode the text that you output to the page.
You can implement white-list validation by yourself using regular expression or you can use one of the libraries.

Javascript replace() function adding strange characters

Consider the following Javascript:
var previewImg = 'http://example.com/preview_img/hey.jpg';
var fullImg = previewImg.replace('preview','full');
I would expect the value of fullImg to be:
http://example.com/full_img/hey.jpg
In fact, it is... sort of. Running alert(fullImg); shows the expected url string. But when I deliver that variable to jQuery Fancybox, like this:
jQuery.fancybox.open(fullImg);
Something adds characters into the string, like this:
http://example.com/%EF%BF%BCfull_img/hey.jpg
Where is this %EF%BF%BC coming from? What is it? And most importantly, how do I get rid of it?
Some other clues: This is a Drupal 7 site, running jQuery 1.5.1. I'm using that same Fancybox script elsewhere on the site with no issues.

%EF%BF%BC is a sequence of three URL-encoded characters.
You clearly can't see any unexpected characters in the string. That's because the character sequence %EF%BF%BC is invisible.
It's actually a UTF-8 byte-order mark sequence. This sequence typically comes at the start of a UTF-8 encoded text file. They probably got into your code when you did a copy+paste from another file.
The quickest way to get rid of them is to find the bit of code that was copied+pasted, delete the characters on either side of the problem, and retype them. Depending on your editor, you may find the delete behaves strangely as it deletes the hidden characters.
Some text editors and IDEs will have an option to show hidden characters. If your editor has this, it may help you see where the mystery characters are so you can delete them.
Hope that helps.

My regex breaks when I "alert" it - because of escaped slashes?

I'm currently working on a CKEditor plugin which would add internal links to our CMS. One of the thing their current link plugin does is that it'll parse through a link when it loads the link dialog to figure out what "type" it is.
Since I created the internal type I need to add a regular expression to compare it to and I'm having trouble doing so. I managed to match my expression using this tool but once I use the same expression in the RegExp object definition it doesn't seem to work.
My links look like this:
/en/my_folder_5
or
/fr/my_folder_5
I tried the following (which worked in that tool):
/(en|fr)/[A-Za-z_^/]+_[0-9]+
but all the slashes get escaped when I "alert" the expression (which leads me to believe it might be what's breaking it since I copy pasted the alerted expression and it did not work)
Any help is appreciated :)

var regex = /\/(en|fr)\/[A-Za-z_^\/]+_[0-9]+/;
alert(regex.test('/fr/my_folder_5')); // prints true