Develop Reference

How do I replace string within quotes in javascript?

I have this in a javascript/jQuery string (This string is grabbed from an html ($('#shortcode')) elements value which could be changed if user clicks some buttons)
[csvtohtml_create include_rows="1-10"
debug_mode="no" source_type="visualizer_plugin" path="map"
source_files="bundeslander_staple.csv" include cols="1,2,4" exclude cols="3"]
In a textbox (named incl_sc) I have the value:
include cols="2,4"
I want to replace include_cols="1,2,4" from the above string with the value from the textbox.
so basically:
How do I replace include_cols values here? (include_cols="2,4" instead of include_cols="1,2,4") I'm great at many things but regex is not one of them. I guess regex is the thing to use here?
I'm trying this:
var s = $('#shortcode').html();
//I want to replace include cols="1,2,4" exclude cols="3"
//with include_cols="1,2" exclude_cols="3" for example
s.replace('/([include="])[^]*?\1/g', incl_sc.val() );
but I don't get any replacement at all (the string s is same string as $("#shortcode").html(). Obviously I'm doing something really dumb. Please help :-)

In short what you will need is
s.replace(/include cols="[^"]+"/g, incl_sc.val());
There were a couple problems with your code,
To use a regex with String.prototype.replace, you must pass a regex as the first argument, but you were actually passing a string.
This is a regex literal /regex/ while this isn't '/actually a string/'
In the text you supplied in your question include_cols is written as include cols (with a space)
And your regex was formed wrong. I recomend testing them in this website, where you can also learn more if you want.
The code above will replace the part include cols="1,2,3" by whatever is in the textarea, regardless of whats between the quotes (as long it doesn't contain another quote).

First of all I think you need to remove the quotes and fix a little bit the regex.
const r = /(include_cols=\")(.*)(\")/g;
s.replace(r, `$1${incl_sc.val()}$3`)
Basically, I group the first and last part in order to include them at the end of the replacement. You can also avoid create the first and last group and put it literally in the last argument of the replace function, like this:
const r = /include_cols=\"(.*)\"/g;
s.replace(r, `include_cols="${incl_sc.val()}"`)

Match between simple delimiters, but not delimiters themselves

I was looking at JSON data that was just in a text file. I don't want to do anything aside from just use regex to get the values in between quotes. I'm just using this as a way to help practice regex and got to this point that seems like it should be simple, but it turns out it's not (at least to me and a few other people at the office). I've matched complicated urls with ease in regex so I'm not completely new to regex. This just seems like a weird case for me.
I've tried:
/(?:")(.*?)(?:")/
/"(.*?)"/
and several others but these got me the closest.
Basically we can forget that it's JSON and just say I want to match the words value and stuff out of "value" and "stuff". Everything I try includes the quotes, so I'd have to clean the strings afterwards of the delimiters or else the string is literally "value" with the quotes.
Any help would be much appreciated, whether this is simple or complicated, I'd love to know! Thanks
Update: Alright so I think I'll go with (?<=")(.*?)(?=") and read things by line without the global setting on so I just get the first match on each line. In my code I was just plopping in a huge string into a var in the code instead of actually opening a file with ajax/filereader or having a form setup to input data. I think I'll mark this as solved, much appreciated!

You have two choices to solve this problem:
Use capturing groups
You can match the delimiters and use capturing groups to get the text within. In this case your two regexes will work, but you need to use access capturing group 1 to get the results (demo). See How do you access the matched groups in a JavaScript regular expression? for how to do that.
Use zero-width assertions
You can use zero-width assertions to match only the text within, require delimiters around them without actually matching them (demo):
(?<=")(.*?)(?=")
but now since I'm not consuming the quotes it'll find instances between each quote, not just between pairs of quotes: e.g., a"b"c" would find b and c.
As for getting just the first match, I think that'll happen by default in JavaScript. You'd have to ask for repeated matching before you see the subsequent ones. So if you process your file one line at a time, you should get what you want.

get the values in between quotes
One thing to keep in mind is that valid JSON accepts escaped quotes inside the quoted values. Therefore, the RegEx should take this into account when capturing the groups which is done with the “unrolling-the-loop” pattern.
var pattern = /"[^"\\]*(?:\\.[^"\\]*)*"/g;
var data = {
"value": "This is \"stuff\".",
"empty": "",
"null": null,
"number": 50
};
var dataString = JSON.stringify(data);
console.log(dataString);
var matched = dataString.match(pattern);
matched.map(item => console.log(JSON.parse(item)));

regex replace on JSON is removing an Object from Array

I'm trying to improve my understanding of Regex, but this one has me quite mystified.
I started with some text defined as:
var txt = "{\"columns\":[{\"text\":\"A\",\"value\":80},{\"text\":\"B\",\"renderer\":\"gbpFormat\",\"value\":80},{\"text\":\"C\",\"value\":80}]}";
and do a replace as follows:
txt.replace(/\"renderer\"\:(.*)(?:,)/g,"\"renderer\"\:gbpFormat\,");
which results in:
"{"columns":[{"text":"A","value":80},{"text":"B","renderer":gbpFormat,"value":80}]}"
What I expected was for the renderer attribute value to have it's quotes removed; which has happened, but also the C column is completely missing! I'd really love for someone to explain how my Regex has removed column C?
As an extra bonus, if you could explain how to remove the quotes around any value for renderer (i.e. so I don't have to hard-code the value gbpFormat in the regex) that'd be fantastic.

You are using a greedy operator while you need a lazy one. Change this:
"renderer":(.*)(?:,)
^---- add here the '?' to make it lazy
To
"renderer":(.*?)(?:,)
Working demo
Your code should be:
txt.replace(/\"renderer\"\:(.*?)(?:,)/g,"\"renderer\"\:gbpFormat\,");
If you are learning regex, take a look at this documentation to know more about greedyness. A nice extract to understand this is:
Watch Out for The Greediness!
Suppose you want to use a regex to match an HTML tag. You know that
the input will be a valid HTML file, so the regular expression does
not need to exclude any invalid use of sharp brackets. If it sits
between sharp brackets, it is an HTML tag.
Most people new to regular expressions will attempt to use <.+>. They
will be surprised when they test it on a string like This is a
first test. You might expect the regex to match and when
continuing after that match, .
But it does not. The regex will match first. Obviously not
what we wanted. The reason is that the plus is greedy. That is, the
plus causes the regex engine to repeat the preceding token as often as
possible. Only if that causes the entire regex to fail, will the regex
engine backtrack. That is, it will go back to the plus, make it give
up the last iteration, and proceed with the remainder of the regex.
Like the plus, the star and the repetition using curly braces are
greedy.

Try like this:
txt = txt.replace(/"renderer":"(.*?)"/g,'"renderer":$1');
The issue in the expression you were using was this part:
(.*)(?:,)
By default, the * quantifier is greedy by default, which means that it gobbles up as much as it can, so it will run up to the last comma in your string. The easiest solution would be to turn that in to a non-greedy quantifier, by adding a question mark after the asterisk and change that part of your expression to look like this
(.*?)(?:,)
For the solution I proposed at the top of this answer, I also removed the part matching the comma, because I think it's easier just to match everything between quotes. As for your bonus question, to replace the matched value instead of having to hardcode gbpFormat, I used a backreference ($1), which will insert the first matched group into the replacement string.

Don't manipulate JSON with regexp. It's too likely that you will break it, as you have found, and more importantly there's no need to.
In addition, once you have changed
'{"columns": [..."renderer": "gbpFormat", ...]}'
into
'{"columns": [..."renderer": gbpFormat, ...]}' // remove quotes from gbpFormat
then this is no longer valid JSON. (JSON requires that property values be numbers, quoted strings, objects, or arrays.) So you will not be able to parse it, or send it anywhere and have it interpreted correctly.
Therefore you should parse it to start with, then manipulate the resulting actual JS object:
var object = JSON.parse(txt);
object.columns.forEach(function(column) {
column.renderer = ghpFormat;
});
If you want to replace any quoted value of the renderer property with the value itself, then you could try
column.renderer = window[column.renderer];
Assuming that the value is available in the global namespace.
This question falls into the category of "I need a regexp, or I wrote one and it's not working, and I'm not really sure why it has to be a regexp, but I heard they can do all kinds of things, so that's just what I imagined I must need." People use regexps to try to do far too many complex matching, splitting, scanning, replacement, and validation tasks, including on complex languages such as HTML, or in this case JSON. There is almost always a better way.
The only time I can imagine wanting to manipulate JSON with regexps is if the JSON is broken somehow, perhaps due to a bug in server code, and it needs to be fixed up in order to be parseable.

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.

Jquery embedded quote in attribute

I have a custom attribute that is being filled from a database. This attribute can contain an embedded single quote like this,
MYATT='Tony\'s Test'
At some pont in my code I use jquery to copy this attribute to a field like this,
$('#MY_DESC').val($(recdata).attr('MYATT'));
MY_DESC is a text field in a dialog box. When I display the dialog box all I see in the field is
Tony\
What I need to see is,
Tony's Test
How can I fix this so I can see the entire string?

Try:
MYATT='Tony&#x27s Test'
I didn't bother verifying this with the HTML spec, but the wikipedia entry says:
The ability to "escape" characters in this way allows for the characters < and & (when written as < and &, respectively) to be interpreted as character data, rather than markup. For example, a literal < normally indicates the start of a tag, and & normally indicates the start of a character entity reference or numeric character reference; writing it as & or & or & allows & to be included in the content of elements or the values of attributes. The double-quote character ("), when used to quote an attribute value, must also be escaped as " or " or " when it appears within the attribute value itself. The single-quote character ('), when used to quote an attribute value, must also be escaped as ' or ' (should NOT be escaped as &apos; except in XHTML documents) when it appears within the attribute value itself. However, since document authors often overlook the need to escape these characters, browsers tend to be very forgiving, treating them as markup only when subsequent text appears to confirm that intent.

In case you won't use double-quotes, put your custom attribute into them :)
If not, I suggest escape the value.

Before setting the value of your text field, you might try running a regular expression against the string to remove all backslashes from the string.

If you do this:
alert($(recdata).attr('MYATT'));
You will see the same result of "Tony\" meaning that the value isn't being properly consumed by the browser. The escaped \' value isn't working in this case.
Do you have the means to edit these values as they are being produced? Can you parse them to include escape values before being rendered?