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How do I let user input curly quotes rather than straight ones by JavaScript in a textarea/input[type=text]? [duplicate]

I have an application which uses a Javascript-based rules engine. I need a way to convert regular straight quotes into curly (or smart) quotes. It’d be easy to just do a string.replace for ["], only this will only insert one case of the curly quote.
The best way I could think of was to replace the first occurrence of a quote with a left curly quote and every other one following with a left, and the rest right curly.
Is there a way to accomplish this using Javascript?

You could replace all that preceed a word character with the left quote, and all that follow a word character with a right quote.
str = str.replace(/"(?=\w|$)/g, "“");
str = str.replace(/(?<=\w|^)"/g, "”"); // IF the language supports look-
// behind. Otherwise, see below.
As pointed out in the comments below, this doesn't take punctuation into account, but easily can:
/(?<=[\w,.?!\)]|^)"/g
[Edit:] For languages that don't support look-behind, like Javascript, as long as you replace all the front-facing ones first, you have two options:
str = str.replace(/"/g, "”"); // Replace the rest with right curly quotes
// or...
str = str.replace(/\b"/g, "”"); // Replace any quotes after a word
// boundary with right curly quotes
(I've left the original solution above in case this is helpful to someone using a language that does support look-behind)

You might want to look at what Pandoc does—apparently with the --smart option, it handles quotes properly in all cases (including e.g. ’tis and ’twere).
I recently wrote a Javascript typography prettification engine that does, among other things, quote replacement; I wound up using basically the algorithm suggested by Renesis, but there’s currently a failing test up waiting for a smarter solution.
If you’re interested in cribbing my code (and/or submitting a patch based on work you’ve done), check it out: jsPrettify. jsprettify.prettifyStr does what you’re looking for. If you don’t want to deal with the Closure dependency, there’s an older version that runs on its own—it even works in Rhino.

'foo "foo bar" "bar"'.replace(/"([-a-zA-Z0-9 ]+)"/g, function(wholeMatch, m1){
return "“" + m1 + "”";
});

The following just changes every quote by alternating (this specific example however would leave out the orphaned quotes).
str.replace(/\"([^\"]*)\"/gi,"“$1”");
Works perfectly, as long as the text you're texturizing isn't already screwed up with improper use of the double quote. In English, quotes are never nested.

I don't think something like that in general is easy at all, because you'd have to interpret exactly what each double-quote character in your content means. That said, what I'd do is collect all the text nodes I was interested in, and then go through and keep track of the "on/off" (or "odd/even"; whatever) nature of each double quote instance. Then you can know which replacement entity to use.

I didn't find the logic I wanted here, so here's what I ended up going with.
value = value.replace(/(^|\s)(")/g, "$1“"); // replace quotes that start a line or follow spaces
value = value.replace(/"/g, "”"); // replace rest of quotes with the back smart quote
I have a small textarea that I need to replace straight quotes with curly (smart) quotes. I'm just executing this logic on keyup. I tried to make it behave like Microsoft Word.

Posting for posterity.
As suggested by #Steven Dee, I went to Pandoc.
I try to use a mature and tested tool whenever I can versus baking my own regex. Hand built regex's can be overly greedy, or not greedy enough, and they may not be sensitive to word boundaries and commas etc. Pandoc accounts for most this and more.
From the command line (the --smart parameter turns on smart quotes):
pandoc --smart --standalone -o output.html input.html
..and I know a command line script may or may not fit OP's requirement of using Javascript. (related: How to execute shell command in Javascript)

Parse JS code for comments

I have a small NodeJS program that I use to extract code comments from files I point it to. It mostly works, but I'm having some issues dealing with it misinterpreting certain JS strings (glob patterns) as code comments.
I'm using the regex [^:](\/\/.+)|(\/\*[\W\w\n\r]+?\*\/) to parse the following test file:
function DoStuff() {
/* This contains the value of foo.
Foo is used to display "foo"
via http://stackoverflow.com
*/
this.foo = "http://google.com";
this.protocolAgnosticUrl = "//cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/core.js";
//Show a message about foo
alert(this.foo);
/// This is a triple-slash comment!
const globPatterns = [
'path/to/**/*.tests.js',
'!my-file.js',
"!**/folder/*",
'another/path/**/*.tests.js'
];
}
Here's a live demo to help visualize what is and is not properly captured by the regex: https://regex101.com/r/EwYpQl/1
I need to be able to only locate the actual code comments here, and not the comment-like syntax that can sometimes appear within strings.

I have to agree with the comments that for most cases it is better to use a parser, even when a RegExp can do the job for a specific and well defined use case.
The problem is not that you can't make it work for that very specific use case even thought there are probably plenty of edge cases that you don't really care about, nor have to, but that may break that solution. The actual problem is that if you start building around your sub-optimal solution and your requirements evolve overtime, you will start to patch those as they appear. Someday, you may find yourself with an extensive codebase full of patches that doesn't scale anymore and the only solution will probably be to start from scratch.
Anyway, you have been warned by a few of us, and is still possible that your use case is really that simple and will not change in the future. I would still consider moving from RegExp to a parser at some point, but maybe you can use this meanwhile:
(^ +\/\/(.*))|(["'`]+.*["'`]+.*\/\/(.*))|(["'`]+.*["'`]+.*\/\*([\W\w\n\r]+?)\*\/)|(^ +\/\*([\W\w\n\r]+?)\*\/)
Just in case, I have added a few other cases, such as comments that come straight after some valid code:
Edit to prove the first point and what is being said in the comments:
I have just answered this with the previous RegExp that was solving just the issue that you pointed out in your question (your RegExp was misinterpreting strings containing glob patterns as code comments).
So, I fixed that and I even made it able to match comments that start in the same line as a valid (non-commented) statement. Just a moment after posting that I notice that this last feature will only work if that statement contains a string.
This is the updated version, but please, keep in mind that this is exactly what we are warning you about...:
(^[^"'`\n]+\/\/(.*))|(["'`]+.*["'`]+.*\/\/(.*))|(["'`]+.*["'`]+.*\/\*([\W\w\n\r]+?)\*\/)|(^[^"'`\n]+\/\*([\W\w\n\r]+?)\*\/)
How does it work?
There are 4 main groups that compose the whole RegExp, the first two for single-line comments and the next two for multi-line comments:
(^[^"'`\n]+//(.*))
(["']+.*["']+.//(.))
(["']+.*["']+.*/*([\W\w\n\r]+?)*/)
(^[^"'`\n]+/*([\W\w\n\r]+?)*/)
You will see there are some repeated patterns:
^[^"'`\n]+: From the start of a line, match anything that doesn't include any kind of quote or line break.
` is for ES2015 template literals.
Line breaks are excluded as well to prevent matching empty lines.
Note the + will prevent matching comments that are not padded with at least one space. You can try replacing it with *, but then it will match strings containing glob patterns again.
["']+.*["']+.*: This is matching anything that is between quotes, including anything that looks like a comment but it's part of a string. Whatever you match after, it will be outside that string, so using another group you can match comments.

Confused with Regex JS pattern

ok i do have this following data in my div
<div id="mydiv">
<!--
what is your present
<code>alert("this is my present");</code>
where?
<code>alert("here at my left hand");</code>
oh thank you! i love you!! hehe
<code>alert("welcome my honey ^^");</code>
-->
</div>
well what i need to do there is to get the all the scripts inside the <code> blocks and the html codes text nodes without removing the html comments inside. well its a homework given by my professor and i can't modify that div block..
I need to use regular expressions for this and this is what i did
var block = $.trim($("div#mydiv").html()).replace("<!--","").replace("-->","");
var htmlRegex = new RegExp(""); //I don't know what to do here
var codeRegex = new RegExp("^<code(*n)</code>$","igm");
var code = codeRegex.exec(block);
var html = "";
it really doesn't work... please don't give the exact answer.. please teach me.. thank you
I need to have the following blocks for the variable code
alert("this is my present");
alert("here at my left hand");
alert("welcome my honey ^^");
and this is the blocks i need for variable html
what is your present
where?
oh thank you! i love you!! hehe
my question is what is the regex pattern to get the results above?

Parsing HTML with a regular expression is not something you should do.
I'm sure your professor thinks he/she was really clever and that there's no way to access the DOM API and can wave a banner around and justify some minor corner-case for using regex to parse the DOM and that sometimes it's okay.
Well, no, it isn't. If you have complex code in there, what happens? Your regex breaks, and perhaps becomes a security exploit if this is ever in production.
So, here:
http://jsfiddle.net/zfp6D/
Walk the dom, get the nodeType 8 (comment) text value out of the node.
Invoke the HTML parser (that thing that browsers use to parse HTML, rather than regex, why you wouldn't use the HTML parser to parse HTML is totally beyond me, it's like saying "Yeah, I could nail in this nail with a hammer, but I think I'm going to just stomp on the nail with my foot until it goes in").
Find all the CODE elements in the newly parsed HTML.
Log them to console, or whatever you want to do with them.

First of all, you should be aware that because HTML is not a regular language, you cannot do generic parsing using regular expressions that will work for all valid inputs (generic nesting in particular cannot be expressed with regular expressions). Many parsers do use regular expressions to match individual tokens, but other algorithms need to be built around them
However, for a fixed input such as this, it's just a case of working through the structure you have (though it's still often easier to use different parsing methods than just regular expressions).
First lets get all the code:
var code = '', match = [];
var regex = new RegExp("<code>(.*?)</code>", "g");
while (match = regex.exec(content)) {
code += match[1] + "\n";
}
I assume content contains the content of the div that you've already extracted. Here the "g" flag says this is for "global" matching, so we can reuse the regex to find every match. The brackets indicate a capturing group, . means any character, * means repeated 0 or more times, and ? means "non-greedy" (see what happens without it to see what it does).
Now we can do a similar thing to get all the other bits, but this time the regex is slightly more complicated:
new RegExp("(<!--|</code>)(.*?)(-->|<code>)", "g")
Here | means "or". So this matches all the bits that start with either "start comment" or "end code" and end with "end comment" or "start code". Note also that we now have 3 sets of brackets, so the part we want to extract is match[2] (the second set).

You're doing a lot of unnecessary stuff. .html() gives you the inner contents as a string. You should be able to use regEx to grab exactly what you need from there. Also, try to stick with regEx literals (e.g. /^regexstring$/). You have to escape escape characters using new RegExp which gets really messy. You generally only want to use new RegExp when you need to put a string var into a regEx.
The match function of strings accepts regEx and returns a collection of every match when you add the global flag (e.g. /^regexstring$/g <-- note the 'g'). I would do something like this:
var block = $('#mydiv').html(), //you can set multiple vars in one statement w/commas
matches = block.match(/<code>[^<]*<\/code>/g);
//[^<]* <-- 0 or more characters that aren't '<' - google 'negative character class'
matches.join('_') //lazy way of avoiding a loop - join into a string with a safe character
.replace(/<\/*code>/g,'') //\/* 0 or more forward slashes
.split('_');//return the matches string back to array
//Now do what you want with matches. Eval (ew) or append in a script tag (ew).
//You have no control over the 'ew'. I just prefer data to scripts in strings

Regex extraction of one letter inside html chunk

Hi need to extract ONE letter from a string.
The string i have is a big block of html, but the part where i need to search in is this text:
Vahvistustunnus M :
And I need to get the M inside the nbsp's
So, who is the quickest regex-guru out there? :)

Ok, according to this page in the molybdenum api docs, the results will be all of the groups concatenated together. Given that you just want the char between the two 's then it's not good enough to match the whole thing and then pull out the group. Instead you'll need to do something like this:
(?<=Vahvistustunnus )[a-zA-Z](?= )
Warning
This might not work for you because lookbehinds (?<=pattern) are not available in all regex flavors. Specifically, i think that because molybdenum is a firefox extension, then it's likely using ECMA (javascript) regex flavor. And ECMA doesn't support lookbehinds.
If that's the case, then i'm gonna have to ask someone else to answer your question as my regex ninja (amateur) skills don't go much further than that. If you were using the regex in javascript code, then there are ways around this limitation, but based on your description, it sounds like you have to solve this problem with nothing but a raw regex?

Looks like it uses JavaScript and if so
var str = "Vahvistustunnus M :";
var patt = "Vahvistustunnus ([A-Z]) :";
var result = str.match(patt)[1];
should work.

Processing Javascript RegEx submatches

I am trying to write some JavaScript RegEx to replace user inputed tags with real html tags, so [b] will become <b> and so forth. the RegEx I am using looks like so
var exptags = /\[(b|u|i|s|center|code){1}]((.){1,}?)\[\/(\1){1}]/ig;
with the following JavaScript
s.replace(exptags,"<$1>$2</$1>");
this works fine for single nested tags, for example:
[b]hello[/b] [u]world[/u]
but if the tags are nested inside each other it will only match the outer tags, for example
[b]foo [u]to the[/u] bar[/b]
this will only match the b tags. how can I fix this? should i just loop until the starting string is the same as the outcome? I have a feeling that the ((.){1,}?) patten is wrong also?
Thanks

The easiest solution would be to to replace all the tags, whether they are closed or not and let .innerHTML work out if they are matched or not it will much more resilient that way..
var tagreg = /\[(\/?)(b|u|i|s|center|code)]/ig
div.innerHTML="[b][i]helloworld[/b]".replace(tagreg, "<$1$2>") //no closing i
//div.inerHTML=="<b><i>helloworld</i></b>"

AFAIK you can't express recursion with regular expressions.
You can however do that with .NET's System.Text.RegularExpressions using balanced matching. See more here: http://blogs.msdn.com/bclteam/archive/2005/03/15/396452.aspx
If you're using .NET you can probably implement what you need with a callback.
If not, you may have to roll your own little javascript parser.
Then again, if you can afford to hit the server you can use the full parser. :)
What do you need this for, anyway? If it is for anything other than a preview I highly recommend doing the processing server-side.

You could just repeatedly apply the regexp until it no longer matches. That would do odd things like "[b][b]foo[/b][/b]" => "<b>[b]foo</b>[/b]" => "<b><b>foo</b></b>", but as far as I can see the end result will still be a sensible string with matching (though not necessarily properly nested) tags.
Or if you want to do it 'right', just write a simple recursive descent parser. Though people might expect "[b]foo[u]bar[/b]baz[/u]" to work, which is tricky to recognise with a parser.

The reason the nested block doesn't get replaced is because the match, for [b], places the position after [/b]. Thus, everything that ((.){1,}?) matches is then ignored.
It is possible to write a recursive parser in server-side -- Perl uses qr// and Ruby probably has something similar.
Though, you don't necessarily need true recursive. You can use a relatively simple loop to handle the string equivalently:
var s = '[b]hello[/b] [u]world[/u] [b]foo [u]to the[/u] bar[/b]';
var exptags = /\[(b|u|i|s|center|code){1}]((.){1,}?)\[\/(\1){1}]/ig;
while (s.match(exptags)) {
s = s.replace(exptags, "<$1>$2</$1>");
}
document.writeln('<div>' + s + '</div>'); // after
In this case, it'll make 2 passes:
0: [b]hello[/b] [u]world[/u] [b]foo [u]to the[/u] bar[/b]
1: <b>hello</b> <u>world</u> <b>foo [u]to the[/u] bar</b>
2: <b>hello</b> <u>world</u> <b>foo <u>to the</u> bar</b>
Also, a few suggestions for cleaning up the RegEx:
var exptags = /\[(b|u|i|s|center|code)\](.+?)\[\/(\1)\]/ig;
{1} is assumed when no other count specifiers exist
{1,} can be shortened to +

Agree with Richard Szalay, but his regex didn't get quoted right:
var exptags = /\[(b|u|i|s|center|code)](.*)\[\/\1]/ig;
is cleaner. Note that I also change .+? to .*. There are two problems with .+?:
you won't match [u][/u], since there isn't at least one character between them (+)
a non-greedy match won't deal as nicely with the same tag nested inside itself (?)

Yes, you will have to loop. Alternatively since your tags looks so much like HTML ones you could replace [b] for <b> and [/b] for </b> separately. (.){1,}? is the same as (.*?) - that is, any symbols, least possible sequence length.
Updated: Thanks to MrP, (.){1,}? is (.)+?, my bad.

How about:
tagreg=/\[(.?)?(b|u|i|s|center|code)\]/gi;
"[b][i]helloworld[/i][/b]".replace(tagreg, "<$1$2>");
"[b]helloworld[/b]".replace(tagreg, "<$1$2>");
For me the above produces:
<b><i>helloworld</i></b>
<b>helloworld</b>
This appears to do what you want, and has the advantage of needing only a single pass.
Disclaimer: I don't code often in JS, so if I made any mistakes please feel free to point them out :-)

You are right about the inner pattern being troublesome.
((.){1,}?)
That is doing a captured match at least once and then the whole thing is captured. Every character inside your tag will be captured as a group.
You are also capturing your closing element name when you don't need it and are using {1} when that is implied. Below is a cleanup up version:
/\[(b|u|i|s|center|code)](.+?)\[\/\1]/ig
Not sure about the other problem.