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How to Escape the unescaped double quotes in a CSV string in Node

This is very similar to
Regular expression to find unescaped double quotes in CSV file
However, the solutions presented don't work with Node.js's regex engine. Given a CSV string where columns are quoted with double quotes, but some columns have unescaped double quotes in them, what regex could be used to match these unescaped quotes and just remove them.
Example rows
"123","","SDFDS SDFSDF EEE "S"","asdfas","b","lll"
"123","","SDFDS SDFSDF EEE "S"","asdfas","b","lll"
So the two double quotes surrounding the S in the third column would get matched and removed. Needs to work in Node.js (14.16.1)
I have tried (?m)""(?![ \t]*(,|$)) but get a Invalid regular expression: /(?m)""(?![ \t]*(,|$))/: Invalid group exception

I don't know much about node.js, but assuming it is like the JavaScript flavor of regex then I have the following comments about the example you took from the prior answer:
I think your example is choking on the first element, (?m) which is unsupported in Javascript. However, that part is not essential to your task. It only turns on multiline processing and you don't need that if you feed the regex engine each line individually. If you find you still want to feed it a multiline string, then you can still turn on multiline in JavaScript - you do it with the "m" flag after the final delimiter, "/myregex/m". All of the other elements, including the negative lookahead are supported by JavaScript and probably by your engine as well. So, drop the (?m) part of your expression and try it again.
Even after you get it to work, the example row you provided will not be parsed according to your expectations by the sample regular expression. Its function is to identify all occurrences of two double-quotes that are not followed by a comma (or end of string). The ONLY two occurrences of doubled quotes in your example each have a comma after, so you will get no matches on this regex in your example.
It seems like you want some context-sensitive scanning to match and remove the inner pairs of double quotes while leaving the outer ones in place and handling commas inside your strings and possibly correctly quoted double quotes. Regular expression engines are really bad at this kind of processing and I don't think you are going to get satisfactory results whatever you come up with.
You can get an approximate solution to your problem by using regex once to parse the individual elements of the .csv stripping the outer quotes as you go and then running a second regex against each parsed element to either remove single occurrences of double quote or adding a second double-quote, where necessary. Then you can reassemble the string under program control.
This still will break if someone embeds a "", sequence in a data field string, so it's not perfect but it might be good enough for you.
The regex for splitting the .csv and stripping the double quotes is:
/(("(.*?)")|([^,]*))(,|$)/gm
This will accept either a "anything", OR a anything, repeatedly until the source is exhausted. Because of the capturing groups, the parsed text will either by in $3 (if the field was quoted) or $4 (if it was not quoted) but not both.
Here's a regexpReplace of your string with $3&$4 and a semicolon after each iteration (I took the liberty of adding a numeric field without the quotes so you could see that it handles both cases):
"123","","SDFDS SDFSDF EEE "S"",456,"asdfas","b","lll"
RegexpReplace(<above>,"((""(.*?)"")|([^,]*))(,|$)","$3$4;")
=> 123;;SDFDS SDFSDF EEE "S";456;asdfas;b;lll;;
See how the outer quotes have been stripped away. Now it's a simple thing to go through all the matches to remove all the remaining quotes, and then you can reconstruct the string from the array of matches.

Regexp in the Case of Single and Double Quotes

I have the following JavaScript:
let strTest = `
"The issue": "L'oggetto ",
"issue": "oggetto",
"issue": 'oggetto "novo" ',
`;
I'm trying to tokenize a string like the one above.
My regexp attempt:
let regExp = /["'](.*?)["']\s*?:\s*?['"](.*?)["']/gm;
This works fine, except in the case where I have a pair of single quotes (') inside of double quotes (") or vice-versa.
Is this possible with only one regular expression?

I answer my self , I think I came with a smaller regex:
` /["'](.*)["']\s*?:\s*?["'[](.*)["']]/g `
Have a look at regex101.com/r/g9WCbi/1

You can use backreferences:
/(["'])(.*?)\1\s*?:\s*?(['"])(.*?)\3/gm
This will include the quotes, in the tokenized string, but you can then remove them from the produced match by taking only the even numbered tokens.
Edit:
As #TJ Crowder points out, this will not work correctly if the string contains escaped quotes in the form of \" within the string. In order to completely accommodate those escaped quotes and not break on strings like \\"(an escaped backslash preceding a quote) you will need to parse with multiple regexes or take a different tactic
The other thing you might want to look at, if this is coming from JSON, is ignoring regex, and just iterating through the properties of your json object. It depends if the string you're getting is coming in as valid json or not.

How to use quotes within quotes properly

If you create an HTML element with JS using a string like the following, how can you add the extra quotes required within an onclick event? Since I have already exhausted double and single quotes, is there an elegant way of making this work?
var foo_td="<td onclick='window.open('newpage.html', '_blank')'>Open Page</td>";

You need to replace innermost single quotes ' with double quotes " and escape them with single backslash \, like this:
var foo_td="<td onclick='window.open(\"newpage.html\", \"_blank\")'>Open Page</td>";
Demo
Why escape quotes at first place
This is because when the onclick event will be fired on this td and if there are no quotes (if quotes not escaped), then it will look for a variable named newpage.html and _blank and give an error because these variables (most likely) won't exist.
Why not only single backslash with single quote
Single-backslash will only escape the string for the evaluation of this string expresion, and by the time this value is stored in a string it will ignore this backslash.
Why not double backslash with single quote
By the time nodes are rendered on DOM (can check this on Developer Tools of your browser), its attribute values are enclosed inside a double quote rather than a single quote. So, it will be rendered as this and hence give an error.
<div onclick="window.open(\" newpage.html\',="" \'_blank\')'="">Open Page</div>
So, based on three reasons given above you should always escape double quote if you want to pass a string parameter to a function call from an attribute.

Javascript regex ends with pattern

I'm trying to write a regex in javascript to identify string representations of arbitrary javascript functions found in json, ie. something like
{
"key": "function() { return 'I am a function'; }"
}
It's easy enough to identify the start, but I can't figure out how to identify the ending double quotes since the function might also contain escaped double quotes. My best try so far is
/"\s*function\(.*\)[^"]*/g
which works nicely if there are no double quotes in the function string. The end of a json key value will end with a double quote and a subsequent comma or closing bracket. Is there some way to retrieve all characters (including newline?) until a negated pattern such as
not "/s*, and not "/s*}
... or do I need to take a completely different approach without regex?
Here's is the current test data I'm working with:
http://regexr.com/39pvi

Seems like you want something like this,
"\s*function\(.*\)(?:\\.|[^\\"])*
It matches also the inbetween \" escaped double quotes.
DEMO

How can I accommodate a string with both single and double quotes inside of it in JavaScript

I have an application, and it is fed some HTML. It then needs to put that HTML into a string. This HTML contains single and double quotes. Is it possible, in javascript, to declare a string with information inside of it, that does not use single or double quotes?
I guess if it is not possible, does anyone know a simple and easy way to escape these quotes so I can put it in a string? Keep in mind, part of this string will be JavaScript that I will later need to execute.

You need to escape the quotation characters with \:
var someString = 'escape all the quotation marks \"\'';

Is it possible, in javascript, to declare a string with information inside of it, that does not use single or double quotes?
No. JavaScript string literals are delimited with either single quotes or double quotes. Those are the only choices.
does anyone know a simple and easy way to escape these quotes so I can put it in a string?
Do you mean in a string literal?
var str = "var foo=\"bar\"; function say(it) { alert('It is: ' + it); say(foo);";
Or programmatically?
str = str.replace(/"/g, '\\"');

An easy way to escape the quotes is to use the javascript escape function.
http://www.w3schools.com/jsref/jsref_escape.asp

Use the escape function to replace special characters (including single and double quotes). You can then use the unescape function to return the string to it's normal state later if necessary.
For example:
var data = 'hello my name is "James"';
alert(escape(data)); //Outputs: hello%20my%20name%20is%20%22James%22