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Regex - to extract text before the last a hyphen/dash

Example data expected output
sds-rwewr-dddd-cash0-bbb cash0
rrse-cash1-nonre cash1
loan-snk-cash2-ssdd cash2
garb-cash3-dfgfd cash3
loan-unwan-cash4-something cash4
The common pattern is here, need to extract a few chars before the last hyphen of given string.
var regex1= /.*(?=(?:-[^-]*){1}$)/g ; //output will be "ds-rwewr-dddd-cash0" from "sds-rwewr-dddd-cash0-bbb "
var regex2 = /\w[^-]*$/g ; //output will be "cash0" from "ds-rwewr-dddd-cash0"
var res =regex2.exec(regex1.exec(sds-rwewr-dddd-cash0-bbb)) //output will cash0
Although above nested regex is working as expected but may not be optimize one. So any help will be appreciated for optimized regex

You can use
/\w+(?=-[^-]*$)/
If the part before the last hyphen can contain chars other than word chars, keep using \w[^-]*: /\w[^-]*(?=-[^-]*$)/. If you do not need to check the first char of your match, simply use /[^-]+(?=-[^-]*$)/.
See the regex demo.
Details:
\w+ - one or more word chars
(?=-[^-]*$) - that must be followed with - and then zero or more chars other than - till the end of string.
JavaScript demo
const texts = ['sds-rwewr-dddd-cash0-bbb','rrse-cash1-nonre','loan-snk-cash2-ssdd','garb-cash3-dfgfd','loan-unwan-cash4-something'];
const regex = /\w+(?=-[^-]*$)/;
for (var text of texts) {
console.log(text, '=>', text.match(regex)?.[0]);
}

Regex to extract two numbers with spaces from string

I have problem with simple rexex. I have example strings like:
Something1\sth2\n649 sth\n670 sth x
Sth1\n\something2\n42 036 sth\n42 896 sth y
I want to extract these numbers from strings. So From first example I need two groups: 649 and 670. From second example: 42 036 and 42 896. Then I will remove space.
Currently I have something like this:
\d+ ?\d+
But it is not a good solution.

You can use
\n\d+(?: \d+)?
\n - Match new line
\d+ - Match digit from 0 to 9 one or more time
(?: \d+)? - Match space followed by digit one or more time. ( ? makes it optional )
let strs = ["Something1\sth2\n649 sth\n670 sth x","Sth1\n\something2\n42 036 sth\n42 896 sth y"]
let extractNumbers = str => {
return str.match(/\n\d+(?: \d+)?/g).map(m => m.replace(/\s+/g,''))
}
strs.forEach(str=> console.log(extractNumbers(str)))

If you need to remove the spaces. Then the easiest way for you to do this would be to remove the spaces and then scrape the numbers using 2 different regex.
str.replace(/\s+/, '').match(/\\n(\d+)/g)
First you remove spaces using the \s token with a + quantifier using replace.
Then you capture the numbers using \\n(\d+).
The first part of the regex helps us make sure we are not capturing numbers that are not following a new line, using \ to escape the \ from \n.
The second part (\d+) is the actual match group.

var str1 = "Something1\sth2\n649 sth\n670 sth x";
var str2 = "Sth1\n\something2\n42 036 sth\n42 896 sth y";
var reg = /(?<=\n)(\d+)(?: (\d+))?/g;
var d;
while(d = reg.exec(str1)){
console.log(d[2] ? d[1]+d[2] : d[1]);
}
console.log("****************************");
while(d = reg.exec(str2)){
console.log(d[2] ? d[1]+d[2] : d[1]);
}

JavaScript regex to remove special characters and remove extra spaces while leaving commas

I'm trying to do two things to clean the string, the first is to remove any space and replace it with a comma separator, the second is to remove any non-alphanumeric characters (other than the comma); I have the first part functional, but now I can't figure out how to remove the special characters as well:
$("#fancydiv").keyup(function(e) {
var str = this.value.replace(/(\w)[\s,]+(\w?)/g, '$1,$2');
if (str!=this.value) this.value = str;
});

'?no, special-characters!'.replace(/[^\w,]/g, '')
// => "no,specialcharacters"
[^\w,] will match match non-alphabet, non-digit, non-underscore character excluding a comma.

Try this:
var str = this.value.replace(/\s/g, ',').replace(/[^\w,]/g, '');

Javascript Split Space Delimited String and Trim Extra Commas and Spaces

I need to split a keyword string and turn it into a comma delimited string. However, I need to get rid of extra spaces and any commas that the user has already input.
var keywordString = "ford tempo, with,,, sunroof";
Output to this string:
ford,tempo,with,sunroof,
I need the trailing comma and no spaces in the final output.
Not sure if I should go Regex or a string splitting function.
Anyone do something like this already?
I need to use javascript (or JQ).
EDIT (working solution):
var keywordString = ", ,, ford, tempo, with,,, sunroof,, ,";
//remove all commas; remove preceeding and trailing spaces; replace spaces with comma
str1 = keywordString.replace(/,/g , '').replace(/^\s\s*/, '').replace(/\s\s*$/, '').replace(/[\s,]+/g, ',');
//add a comma at the end
str1 = str1 + ',';
console.log(str1);

You will need a regular expression in both cases. You could split and join the string:
str = str.split(/[\s,]+/).join();
This splits on and consumes any consecutive white spaces and commas. Similarly, you could just match and replace these characters:
str = str.replace(/[\s,]+/g, ',');
For the trailing comma, just append one
str = .... + ',';
If you have preceding and trailing white spaces, you should remove those first.
Reference: .split, .replace, Regular Expressions

In ES6:
var temp = str.split(",").map((item)=>item.trim());

In addition to Felix Kling's answer
If you have preceding and trailing white spaces, you should remove
those first.
It's possible to add an "extension method" to a JavaScript String by hooking into it's prototype. I've been using the following to trim preceding and trailing white-spaces, and thus far it's worked a treat:
// trims the leading and proceeding white-space
String.prototype.trim = function()
{
return this.replace(/^\s\s*/, '').replace(/\s\s*$/, '');
};

I would keep it simple, and just match anything not allowed instead to join on:
str.split(/[^a-zA-Z-]+/g).filter(v=>v);
This matches all the gaps, no matter what non-allowed characters are in between. To get rid of the empty entry at the beginning and end, a simple filter for non-null values will do. See detailed explanation on regex101.
var str = ", ,, ford, tempo, with,,, sunroof,, ,";
var result = str.split(/[^a-zA-Z-]+/g).filter(v=>v).join(',');
console.info(result);

let query = "split me by space and remove trailing spaces and store in an array ";
let words = query.trim().split(" ");
console.log(words)
Output :
[
'split', 'me', 'by', 'space','and','remove', 'trailing', 'spaces', 'and', 'store', 'in', 'an', 'array'
]

If you just want to split, trim and join keeping the whitespaces, you can do this with lodash:
// The string to fix
var stringToFix = "The Wizard of Oz,Casablanca,The Green Mile";
// split, trim and join back without removing all the whitespaces between
var fixedString = _.map(stringToFix.split(','), _.trim).join(' == ');
// output: "The Wizard of Oz == Casablanca == The Green Mile"
console.log(fixedString);
<script src="https://cdn.jsdelivr.net/lodash/4.16.3/lodash.min.js"></script>

How can I replace newlines/line breaks with spaces in javascript?

I have a var that contains a big list of words (millions) in this format:
var words = "
car
house
home
computer
go
went
";
I want to make a function that will replace the newline between each word with space.
So the results would something look like this:
car house home computer go went

You can use the .replace() function:
words = words.replace(/\n/g, " ");
Note that you need the g flag on the regular expression to get replace to replace all the newlines with a space rather than just the first one.
Also, note that you have to assign the result of the .replace() to a variable because it returns a new string. It does not modify the existing string. Strings in Javascript are immutable (they aren't directly modified) so any modification operation on a string like .slice(), .concat(), .replace(), etc... returns a new string.
let words = "a\nb\nc\nd\ne";
console.log("Before:");
console.log(words);
words = words.replace(/\n/g, " ");
console.log("After:");
console.log(words);

In case there are multiple line breaks (newline symbols) and if there can be both \r or \n, and you need to replace all subsequent linebreaks with one space, use
var new_words = words.replace(/[\r\n]+/g," ");
See regex demo
To match all Unicode line break characters and replace/remove them, add \x0B\x0C\u0085\u2028\u2029 to the above regex:
/[\r\n\x0B\x0C\u0085\u2028\u2029]+/g
The /[\r\n\x0B\x0C\u0085\u2028\u2029]+/g means:
[ - start of a positive character class matching any single char defined inside it:
\r - (\x0D) - \n] - a carriage return (CR)
\n - (\x0A) - a line feed character (LF)
\x0B - a line tabulation (LT)
\x0C - form feed (FF)
\u0085 - next line (NEL)
\u2028 - line separator (LS)
\u2029 - paragraph separator (PS)
] - end of the character class
+ - a quantifier that makes the regex engine match the previous atom (the character class here) one or more times (consecutive linebreaks are matched)
/g - find and replace all occurrences in the provided string.
var words = "car\r\n\r\nhouse\nhome\rcomputer\ngo\n\nwent";
document.body.innerHTML = "<pre>OLD:\n" + words + "</pre>";
var new_words = words.replace(/[\r\n\x0B\x0C\u0085\u2028\u2029]+/g," ");
document.body.innerHTML += "<pre>NEW:\n" + new_words + "</pre>";

Code : (FIXED)
var new_words = words.replace(/\n/g," ");

Some simple solution would look like
words.replace(/(\n)/g," ");

No need for global regex, use replaceAll instead of replace
myString.replaceAll('\n', ' ')

const words = `He had
concluded that pigs
must be able
to fly in Hog Heaven.
`
document.body.innerHTML = "<pre>without-Trim-And-Remove:\n" + words + "</pre>";
trimAndRemoveSymbols=(text)=>{
return text.replace(/[\n]+/g, '').trim();
}
document.body.innerHTML += "<pre>Trim-And-Remove:\n" + trimAndRemoveSymbols(words) + "</pre>";