Develop Reference

Regex finding second string

I'm attempting to get the last word in the following strings.
After about 45 minutes I can't seem to find the right combination of slashes, dashes and brackets.
The closest I've got is
/(?![survey])[a-z]+/gi
It matches the following strings, except for "required" it is returning the match "quired" I'm assuming it's because the re are in the word survey.
survey[1][title]
survey[1][required]
survey[2][anotherString]

You're using a character set, which will exclude any of the characters from being the first character in the match, which isn't what you want. Using plain negative lookahead would be a start:
(?!survey)[a-z]+
But you also want to match the final word, which can be done by matching word characters that are followed with \]$ - that is, by a ] and the end of the string:
[a-z]+(?=\]$)
https://regex101.com/r/rLvsY5/1
If you want to be more efficient, match the whole string, but capture what comes between the square brackets in a capturing group - the last repeated captured group will be in the result:
survey(?:\[(\w+)\])+
https://regex101.com/r/rLvsY5/2

One way to solve this is to match the full line and only capture the part you need.
survey\[\d+\]\[([a-z]+)\]

Why isn't this group capturing all items that appear in parentheses?

I'm trying to create a regex that will capture a string not enclosed by parentheses in the first group, followed by any amount of strings enclosed by parentheses.
e.g.
2(3)(4)(5)
Should be: 2 - first group, 3 - second group, and so on.
What I came up with is this regex: (I'm using JavaScript)
([^()]*)(?:\((([^)]*))\))*
However, when I enter a string like A(B)(C)(D), I only get the A and D captured.
https://regex101.com/r/HQC0ib/1
Can anyone help me out on this, and possibly explain where the error is?

Since you cannot use a \G anchor in JS regex (to match consecutive matches), and there is no stack for each capturing group as in a .NET / PyPi regex libraries, you need to use a 2 step approach: 1) match the strings as whole streaks of text, and then 2) post-process to get the values required.
var s = "2(3)(4)(5) A(B)(C)(D)";
var rx = /[^()\s]+(?:\([^)]*\))*/g;
var res = [], m;
while(m=rx.exec(s)) {
res.push(m[0].split(/[()]+/).filter(Boolean));
}
console.log(res);
I added \s to the negated character class [^()] since I added the examples as a single string.
Pattern details
[^()\s]+ - 1 or more chars other than (, ) and whitespace
(?:\([^)]*\))* - 0 or more sequences of:
\( - a (
[^)]* - 0+ chars other than )
\) - a )
The splitting regex is [()]+ that matches 1 or more ) or ( chars, and filter(Boolean) removes empty items.

You cannot have an undetermined number of capture groups. The number of capture groups you get is determined by the regular expression, not by the input it parses. A capture group that occurs within another repetition will indeed only retain the last of those repetitions.
If you know the maximum number of repetitions you can encounter, then just repeat the pattern that many times, and make each of them optional with a ?. For instance, this will capture up to 4 items within parentheses:
([^()]*)(?:\(([^)]*)\))?(?:\(([^)]*)\))?(?:\(([^)]*)\))?(?:\(([^)]*)\))?

It's not an error. It's just that in regex when you repeat a capture group (...)* that only the last occurence will be put in the backreference.
For example:
On a string "a,b,c,d", if you match /(,[a-z])+/ then the back reference of capture group 1 (\1) will give ",d".
If you want it to return more, then you could surround it in another capture group.
--> With /((?:,[a-z])+)/ then \1 will give ",b,c,d".
To get those numbers between the parentheses you could also just try to match the word characters.
For example:
var str = "2(3)(14)(B)";
var matches = str.match(/\w+/g);
console.log(matches);

Replace last character of a matched string using regex

I am need to post-process lines in a file by replacing the last character of string matching a certain pattern.
The string in question is:
BRDA:2,1,0,0
I'd like to replace the last digit from 0 to 1. The second and third digits are variable, but the string will always start BRDA:2 that I want to affect.
I know I can match the entire string using regex like so
/BRDA:2,\d,\d,1
How would I get at that last digit for performing a replace on?
Thanks

You may match and capture the parts of the string with capturing groups to be able to restore those parts in the replacement result later with backreferences. What you need to replace/remove should be just matched.
So, use
var s = "BRDA:2,1,0,0"
s = s.replace(/(BRDA:2,\d+,\d+,)\d+/, "$11")
console.log(s)
If you need to match the whole string you also need to wrap the pattern with ^ and $:
s = s.replace(/^(BRDA:2,\d+,\d+,)\d+$/, "$11")
Details:
^ - a start of string anchor
(BRDA:2,\d+,\d+,) - Capturing group #1 matching:
BRDA:2, - a literal sunstring BRDA:2,
\d+ - 1 or more digits
, - a comma
\d+, - 1+ digits and a comma
\d+ - 1+ digits.
The replacement - $11 - is parsed by the JS regex engine as the $1 backreference to the value kept inside Group 1 and a 1 digit.

Catching start number and final number

i'm trying to create a regex to catch the first number in the line and the last one, but i'm having some problem with the last one:
The lines look like this:
00005 SALARIO MENSAL 17030 36.397.291,92 36.397.291,92
00010 HORAS TRABALHADAS 0798 19.731,93 19.731,93
And this is my regex:
(^\d+).*(\d)
As you can see here: http://regexr.com/3crbt is not working as expected. I can get the first one, but the last is just the last number.
Thanks!

You can use
/^(\d+).*?(\d+(?:[,.]\d+)*)$/gm
See the regex demo
The regex matches:
^ - start of the line
(\d+) - captures into Group 1 one or more digits
.*? - matches any characters but a newline, as few as possible up to
(\d+(?:[,.]\d+)*) - one or more digits followed with zero or more sequences of , or . followed with one or more digits (Group 2)
$ - end of the string
The /g modifier ensures we get all matches and /m modifier makes the ^ and $ match start and end of a line respectively.

I tried the following one:
(^(\d+))|(\d+$)
And its seems to work on the regexr.com thingy. But matching them up might require some assumptions that each line has at least two numbers.

You need to make the .* non-greedy by changing it to .*? and add + to the second digit sequence match.
^(\d+).*?(\d+)$
If you want to match the full last number, use this:
^(\d+).*?([\d\.,]+)$
Example

Javascript RegEx to check a certain number of Numeric characters in string regardless of other characters

I have a field which the user will be entering a 9 digit numeric string.
e.g. 975367865
However some users will be entering the 9 digit numeric string with seperators such as "-" and "/".
e.g. 9753/67/865 OR 9753-67-865
I want to make sure that the user has entered a minimum of 9 numbers even if the user has added the "-" & "/" somewhere in the string.
Hope that makes sense.
Many thanks for any help.

You could just remove anything that is not a number to give a nice normalized form:
var number = input.replace(/[^\d]/g, "");
var ok = number.length == 9;

Match with a quantifier:
/^\d(?:\D*\d){8}$/
^$ are Anchors that asserts position at the start of end of the String. This asserts the entire match, but since you're only matching, you can leave them out!
\d matches a digit.
\D* skips ahead of any non-digits. Then a digit will be matched with \d.
This group is then quantified: (?: ){8} To assert that the later alternation is matched eight times. Parted with the first match, this asserts that 9 digits are present in the match!
View an online regex demo!

(?=[\-\/]*[0-9][\-\/]*[0-9][\-\/]*[0-9][\-\/]*[0-9][\-\/]*[0-9][\-\/]*[0-9][\-\/]*[0-9][\-\/]*[0-9][\-\/]*[0-9]+[\-\/]*)(.*)
Though a rather long looking regex but works perfectly well for your case.
Have a look at the demo.
http://regex101.com/r/uR2aE4/3