Develop Reference

How to use the speciale character '\' in a string in node [duplicate]

I am passing a path as an argument in a Javascript.
For example I am passing a path as c:\my documents\user\aa.jpg when registering Javascript in client side.
When calling this in a function say, function js(d) then the slash goes missing, hence the value of 'd' becomes c:mydocumentsuseraa.jpg
What to do?

Have you escaped your backslashes ?
alert( 'c:\\my documents\\user\\aa.jpg' );

pass it like this:
c:\\my documents\\user\\aa.jpg
you need to escape the slash char. thanks
You should always pass the slash char
which has special meaning for example,
you can use it to specify new lines
like \n, tabs \t, etc. So you should
escape it with another slash char to
make it come single slash char.

You said when registering javascript in client side.
I assume you are doing this in the code behind as you have tagged asp.net.
So I think you would need to use # before the string while registering the scipt.
Like #"c:\abc\xyz.jpg"
OR you can go by the method Sarfraz mentiond. i.e. pass the string as "c:\\abc\\xyz.jpg"
I hope this helps.

How to split a string in javascript by special char \

I believe that this is simple and I'm missing something. I want to split a physical path in windows with javascript. So I try with String#split function, but my result was inespected.
For this string
"C:\CLC\VIDA\Web\_REPOSITORIO\Colectivos\ReembolsosWeb\TMP_011906169_01_01.pdf"
I'm getting this result
var test = "C:\CLC\VIDA\Web\_REPOSITORIO\Colectivos\ReembolsosWeb\TMP_011906169_01_01.pdf";
test.split("\"); //throws error
test.split("\\"); //result in -> ["C:CLCVIDAWeb_REPOSITORIOColectivosReembolsosWebTMP_011906169_01_01.pdf"]
test.split(/\\/); // -> the regex is the same as above
One last thing, in my test, I found that to get the result that I want I could do it like this
var test2 = "C:\\CLC\\VIDA\\Web\\_REPOSITORIO\\Colectivos\\ReembolsosWeb\\TMP_011906169_01_01.pdf"
test2.split("\\"); // -> ["C:", "CLC", "VIDA", "Web", "_REPOSITORIO", "Colectivos", "ReembolsosWeb", "TMP_011906169_01_01.pdf"]
So my question is, how can I split the string from test var to get the array from the last case?

Strings in javascript support escape sequences via the backslash (\). For example if you need a tab in your string you can add a \t anywhere in your string and it will be replaced with a tab, a \n will be replaced with a new line.
The backslashes in test are either converted to their respective characters or dropped because they are invalid escape sequences.
To get around this you can escape one backslash with another to get a single normal backslash. The downside is that this cannot be done in javascript. Generally I paste my string in to notepad/N++/Code/Sublime and replace all \ with \\
Since you are hard coding the string you need to escape all backslashes. After that you can use test.split("\\") which, itself contains an escaped backslash.
So, as far as Javascript is concerned, your code looks like this.
var test = "C:CLCVIDAWeb_REPOSITORIOColectivosReembolsosWebTMP_011906169_01_01.pdf";
To make javascript see the string correctly you need to make it look like this...
var test = "C:\\CLC\\VIDA\\Web\\_REPOSITORIO\\Colectivos\\ReembolsosWeb\\TMP_011906169_01_01.pdf";

Firstly, note that when you have a single backslash in a string, it is used for escaping the next character. It is just ignored if there is no special character next to it to escape.
Now, just have a look at your string :
var test = "C:\CLC\VIDA\Web\_REPOSITORIO\Colectivos\ReembolsosWeb\TMP_011906169_01_01.pdf"
Don't you think all of your single backslashes will be ignored here?
So, the solution is simple, what you have already tried successfully. To escape all your backslashes with another backslash.
var test2 = "C:\\CLC\\VIDA\\Web\\_REPOSITORIO\\Colectivos\\ReembolsosWeb\\TMP_011906169_01_01.pdf"
test2.split("\\"); // -> ["C:", "CLC", "VIDA", "Web", "_REPOSITORIO", "Colectivos", "ReembolsosWeb", "TMP_011906169_01_01.pdf"]
But, are you worried about any dynamic data which has such backslash? (For example, coming from a text input or a file input.) Don't think about escaping the backslash inside it. Because you don't need to do that! It's already a well formatted string for you, which you can use as it is. You need to escape only when you are hard coding the string yourself.

Regex to match all instances not inside quotes

From this q/a, I deduced that matching all instances of a given regex not inside quotes, is impossible. That is, it can't match escaped quotes (ex: "this whole \"match\" should be taken"). If there is a way to do it that I don't know about, that would solve my problem.
If not, however, I'd like to know if there is any efficient alternative that could be used in JavaScript. I've thought about it a bit, but can't come with any elegant solutions that would work in most, if not all, cases.
Specifically, I just need the alternative to work with .split() and .replace() methods, but if it could be more generalized, that would be the best.
For Example:
An input string of: +bar+baz"not+or\"+or+\"this+"foo+bar+
replacing + with #, not inside quotes, would return: #bar#baz"not+or\"+or+\"this+"foo#bar#

Actually, you can match all instances of a regex not inside quotes for any string, where each opening quote is closed again. Say, as in you example above, you want to match \+.
The key observation here is, that a word is outside quotes if there are an even number of quotes following it. This can be modeled as a look-ahead assertion:
\+(?=([^"]*"[^"]*")*[^"]*$)
Now, you'd like to not count escaped quotes. This gets a little more complicated. Instead of [^"]* , which advanced to the next quote, you need to consider backslashes as well and use [^"\\]*. After you arrive at either a backslash or a quote, you need to ignore the next character if you encounter a backslash, or else advance to the next unescaped quote. That looks like (\\.|"([^"\\]*\\.)*[^"\\]*"). Combined, you arrive at
\+(?=([^"\\]*(\\.|"([^"\\]*\\.)*[^"\\]*"))*[^"]*$)
I admit it is a little cryptic. =)

Azmisov, resurrecting this question because you said you were looking for any efficient alternative that could be used in JavaScript and any elegant solutions that would work in most, if not all, cases.
There happens to be a simple, general solution that wasn't mentioned.
Compared with alternatives, the regex for this solution is amazingly simple:
"[^"]+"|(\+)
The idea is that we match but ignore anything within quotes to neutralize that content (on the left side of the alternation). On the right side, we capture all the + that were not neutralized into Group 1, and the replace function examines Group 1. Here is full working code:
<script>
var subject = '+bar+baz"not+these+"foo+bar+';
var regex = /"[^"]+"|(\+)/g;
replaced = subject.replace(regex, function(m, group1) {
if (!group1) return m;
else return "#";
});
document.write(replaced);
Online demo
You can use the same principle to match or split. See the question and article in the reference, which will also point you code samples.
Hope this gives you a different idea of a very general way to do this. :)
What about Empty Strings?
The above is a general answer to showcase the technique. It can be tweaked depending on your exact needs. If you worry that your text might contain empty strings, just change the quantifier inside the string-capture expression from + to *:
"[^"]*"|(\+)
See demo.
What about Escaped Quotes?
Again, the above is a general answer to showcase the technique. Not only can the "ignore this match" regex can be refined to your needs, you can add multiple expressions to ignore. For instance, if you want to make sure escaped quotes are adequately ignored, you can start by adding an alternation \\"| in front of the other two in order to match (and ignore) straggling escaped double quotes.
Next, within the section "[^"]*" that captures the content of double-quoted strings, you can add an alternation to ensure escaped double quotes are matched before their " has a chance to turn into a closing sentinel, turning it into "(?:\\"|[^"])*"
The resulting expression has three branches:
\\" to match and ignore
"(?:\\"|[^"])*" to match and ignore
(\+) to match, capture and handle
Note that in other regex flavors, we could do this job more easily with lookbehind, but JS doesn't support it.
The full regex becomes:
\\"|"(?:\\"|[^"])*"|(\+)
See regex demo and full script.
Reference
How to match pattern except in situations s1, s2, s3
How to match a pattern unless...

You can do it in three steps.
Use a regex global replace to extract all string body contents into a side-table.
Do your comma translation
Use a regex global replace to swap the string bodies back
Code below
// Step 1
var sideTable = [];
myString = myString.replace(
/"(?:[^"\\]|\\.)*"/g,
function (_) {
var index = sideTable.length;
sideTable[index] = _;
return '"' + index + '"';
});
// Step 2, replace commas with newlines
myString = myString.replace(/,/g, "\n");
// Step 3, swap the string bodies back
myString = myString.replace(/"(\d+)"/g,
function (_, index) {
return sideTable[index];
});
If you run that after setting
myString = '{:a "ab,cd, efg", :b "ab,def, egf,", :c "Conjecture"}';
you should get
{:a "ab,cd, efg"
:b "ab,def, egf,"
:c "Conjecture"}
It works, because after step 1,
myString = '{:a "0", :b "1", :c "2"}'
sideTable = ["ab,cd, efg", "ab,def, egf,", "Conjecture"];
so the only commas in myString are outside strings. Step 2, then turns commas into newlines:
myString = '{:a "0"\n :b "1"\n :c "2"}'
Finally we replace the strings that only contain numbers with their original content.

Although the answer by zx81 seems to be the best performing and clean one, it needes these fixes to correctly catch the escaped quotes:
var subject = '+bar+baz"not+or\\"+or+\\"this+"foo+bar+';
and
var regex = /"(?:[^"\\]|\\.)*"|(\+)/g;
Also the already mentioned "group1 === undefined" or "!group1".
Especially 2. seems important to actually take everything asked in the original question into account.
It should be mentioned though that this method implicitly requires the string to not have escaped quotes outside of unescaped quote pairs.

Need a regex for acceptable file names

I'm using Fancy Upload 3 and onSelect of a file I need to run a check to make sure the user doesn't have any bad characters in the filename. I'm currently getting people uploading files with hieroglyphics and such in the names.
What I need is to check if the filename only contains:
A-Z
a-z
0-9
_ (underscore)
- (minus)
SPACE
ÀÈÌÒÙàèìòùÁÉÍÓÚÝáéíóúýÂÊÎÔÛâêîôûÃÑÕãñõÄËÏÖÜäëïöü (as single and double byte)
Obviously you can see the difficult thing there. The non-english single and double byte chars.
I've seen this:
[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]
And this:
[\x80-\xA5]
But neither of them fully cover the situation right.
Examples that should work:
fást.zip
abc.zip
ABC.zip
Über.zip
Examples that should NOT work:
∑∑ø∆.zip
¡wow!.zip
•§ªº¶.zip
The following is close, but I'm NO RegEx'pert, not even close.
var filenameReg = /^[A-Za-z0-9-_]|[\x00A0-\xD7FF\xF900-\xFDCF\xFDF0-\xFFEF]+$/;
Thanks in advance.
Solution from Zafer mostly works, but it does not catch all of the other symbols, see below.
Uncaught:
¡£¢§¶ª«ø¨¥®´åß©¬æ÷µç
Caught:
™∞•–≠'"πˆ†∑œ∂ƒ˙∆˚…≥≤˜∫√≈Ω
Regex:
var filenameReg = /^([A-Za-z0-9\-_. ]|[\x00A0-\xD7FF\xF900-\xFDCF\xFDF0-\xFFEF])+$/;

Alternation between two character classes (ie. [abc]|[def]) can be simplified to a single character class ([abcdef]) -- the first can be read as "(a or b or c) OR (d or e or f)"; the second as "(a or b or c or d or e or f)". What probably tripped up your regular expression is the unescaped dash in the first class -- if you want a literal dash, it should be the last character in the class.
So we'll modify your expression to get it working:
var filenameReg = /^[A-Za-z0-9_\x00A0-\xD7FF\xF900-\xFDCF\xFDF0-\xFFEF-]+$/;
The problem now is that you're not accounting for the file extension, but that is an easy modification (assuming you're always getting .zip files):
var filenameReg = /^[A-Za-z0-9_\x00A0-\xD7FF\xF900-\xFDCF\xFDF0-\xFFEF-]+\.zip$/;
Replace zip with another pattern if the extension differs.

It looks like it is the character ranges that are causing the problem, because they include some unallowable characters in between. Since you already have the list of allowable characters, the best thing would be to just use that directly:
var filenameReg = /^[A-Za-z0-9_\-\ ÀÈÌÒÙàèìòùÁÉÍÓÚÝáéíóúýÂÊÎÔÛâêîôûÃÑÕãñõÄËÏÖÜäëïöü]+$/;

The following should work:
var filenameReg = /^([A-Za-z0-9\-_. ]|[\x00A0-\xD7FF\xF900-\xFDCF\xFDF0-\xFFEF])+$/;
I've put \ next to - and grouped two expressions otherwise + sign doesn't affect the first expression.
EDIT 1 :I've also put . in the expression.

We have diffrent rules for diffrent platforms. But I think you mean long file names in windows. For that you can use following RegEx:
var longFilenames = #"^[^\./:*\?\""<>\|]{1}[^\/:*\?\""<>\|]{0,254}$";
NOTE: Instead of saying which Character is allowed, you need to say which ones are not allowed!
But keep in mind that this is not 100% complete RegEx. If you really want to make it complete you have to add exceptions for reserved names as well.
You can find more information about filename rules here:
http://msdn.microsoft.com/en-us/library/aa365247%28VS.85%29.aspx

Building a Hashtag in Javascript without matching Anchor Names, BBCode or Escaped Characters

I would like to convert any instances of a hashtag in a String into a linked URL:
#hashtag -> should have "#hashtag" linked.
This is a #hashtag -> should have "#hashtag" linked.
This is a [url=http://www.mysite.com/#name]named anchor[/url] -> should not be linked.
This isn't a pretty way to use quotes -> should not be linked.
Here is my current code:
String.prototype.parseHashtag = function() {
return this.replace(/[^&][#]+[A-Za-z0-9-_]+(?!])/, function(t) {
var tag = t.replace("#","")
return t.link("http://www.mysite.com/tag/"+tag);
});
};
Currently, this appears to fix escaped characters (by excluding matches with the amperstand), handles named anchors, but it doesn't link the #hashtag if it's the first thing in the message, and it seems to grab include the 1-2 characters prior to the "#" in the link.
Halp!

How about the following:
/(^|[^&])#([A-Za-z0-9_-]+)(?![A-Za-z0-9_\]-])/g
matches the hashtags in your example. Since JavaScript doesn't support lookbehind, it tries to either match the start of the string or any character except & before the hashtag. It captures the latter so it can later be replaced. It also captures the name of the hashtag.
So, for example:
subject.replace(/(^|[^&])#([A-Za-z0-9_-]+)(?![A-Za-z0-9_\]-])/g, "$1http://www.mysite.com/tag/$2");
will transform
#hashtag
This is a #hashtag and this one #too.
This is a [url=http://www.mysite.com/#name]named anchor[/url]
This isn't a pretty way to use quotes
into
http://www.mysite.com/tag/hashtag
This is a http://www.mysite.com/tag/hashtag and this one http://www.mysite.com/tag/too.
This is a [url=http://www.mysite.com/#name]named anchor[/url]
This isn't a pretty way to use quotes
This probably isn't what t.link() (which I don't know) would have returned, but I hope it's a good starting point.

There is an open-source Ruby gem to do this sort of thing (hashtags and #usernames) called twitter-text. You might get some ideas and regexes from that, or try out this JavaScript port.
Using the JavaScript port, you'll want to just do:
var linked = TwitterText.auto_link_hashtags(text, {hashtag_url_base: "http://www.mysite.come/tag/"});

Tim, your solution was almost perfect. Here's what I ended up using:
subject.replace(/(^| )#([A-Za-z0-9_-]+)(?![A-Za-z0-9_\]-])/g, "$1#$2");
The only change is the first conditional, changed it to match the beginning of the string or a space character. (I tried \s, but that didn't work at all.)