Can someone please help me in defining a regular expression for an endpoint.
person/^((?!-).)*$/
This regex needs to match a number of things but mainly:
person/:id
it should NOT match
person/1234-5678-9123 (it's currently not matching this which is good)
the problem I have is that it should NOT match this but it is:
person/123456789123 (it's currently matching this but shouldn't)
To be clear, If you go to: http://regex101.com and paste in:
^((?!-).)*$
You can see that is matches 123456789123 WHICH IS WRONG
How can I change the RegEx so it doesn't match 123456789123
Cheers.
Your regex ^((?!-).)*$ is same as ^[^-]*$ that is match any charcater but not of - zero or more times.
The reason for why your regex not matches this person/1234-5678-9123 is because it has - symbol. But person/123456789123 string isn't has - symbol, so this got matched.
To match the string which has - between the numbers then you could try the below regex.
^.*?\d+-\d+.*$
OR
^(?=.*?-).+$
(?=.*?-) Positive lookahead asserts that the string must contain an - symbol.
DEMO
Related
I have a few strings:
some-text-123123#####abcdefg/
some-STRING-413123#####qwer123t/
some-STRING-413123#####456zxcv/
I would like to receive:
abcdefg
qwer123t
456zxcv
I have tried regexp:
/[^#####]*[^\/]/
But this not working...
To get whatever comes after five #s and before the last /, you can use
/#####(.*)\//
and pick up the first group.
Demo:
const regex = /#####(.*)\//;
console.log('some-text-123123#####abcdefg/'.match(regex)[1]);
console.log('some-STRING-413123#####qwer123t/'.match(regex)[1]);
console.log('some-STRING-413123#####456zxcv/'.match(regex)[1]);
assumptions:
the desired part of the string sample will always:
start after 5 #'s
end before a single /
suggestion: /(?<=#{5})\w*(?=\/)/
So (?<=#{5}) is a lookbehind assertion which will check to see if any matching string has the provided assertion immediately behind it (in this case, 5 #'s).
(?=\/) is a lookahead assertion, which will check ahead of a matching string segment to see if it matches the provided assertion (in this case, a single /).
The actual text the regex will return as a match is \w*, consisting of a character class and a quantifier. The character class \w matches any alphanumeric character ([A-Za-z0-9_]). The * quantifier matches the preceding item 0 or more times.
successful matches:
'some-text-123123#####abcdefg/'
'some-STRING-413123#####qwer123t/'
'some-STRING-413123#####456zxcv/'
I would highly recommend learning Regular Expressions in-depth, as it's a very powerful tool when fully utilised.
MDN, as with most things web-dev, is a fantastic resource for regex. Everything from my answer here can be learned on MDN's Regular expression syntax cheatsheet.
Also, an interactive tool can be very helpful when putting together a complex regular expression. Regex 101 is typically what I use, but there are many similar web-tools online that can be found from a google search.
You pattern does not work because you are using negated character classes [^
The pattern [^#####]*[^\/] can be written as [^#]*[^\/] and matches optional chars other than # and then a single char other than /
Here are some examples of other patterns that can give the same match.
At least 5 leading # chars and then matching 1+ word chars in a group and the / at the end of the string using an anchor $, or omit the anchor if that is not the case:
#####(\w+)\/$
Regex demo
If there should be a preceding character other than #
[^#]#####(\w+)\/$
(?<!#)#####(\w+)\/$
Regex demo
Matching at least 5 # chars and no # or / in between using a negated character class in this case:
#####([^#\/]+)\/
Or with lookarounds:
(?<=(?<!#)#####)[^#\/]+(?=\/)
Regex demo
I have the following string:
"By signing in, I agree to the {{#a}}[Terms of Use](https://www.example.com/termsofuse){{/a}} and {{#a}}[Privacy Policy](https://www.example.com/privacy){{/a}}."
And I am using the following regex to split the words while considering {{#a}}[Terms of Use](https://www.example.com/termsofuse){{/a}} and {{#a}}[Privacy Policy](https://www.example.com/privacy){{/a}} as whole words.
\s+(?![^\[]*\])
My problem is that my current regex does not remove the full stop at the end of {{#a}}[Privacy Policy](https://www.example.com/privacy){{/a}}.. Ideally I would like my regex to split full stops, exclamation marks and question marks. That being said, I'm not sure how would I differentiate between a full stop at the end of the word and a full stop that is part of the URL.
You can try a variation of the following regular expression:
\s+(?![^\[]*\])|(?=[\.?!](?![a-zA-Z0-9_%-]))
The new part being the alternation of (?=[\.?!](?![a-zA-Z0-9_%-])) at the end. It performs a positive lookahead of a period, question mark or bang, using a negative lookahead to make sure it's not followed by a URL-ish looking character. You may need to adjust that character class in brackets to contain the characters you want to consider part of the URL.
Instead of .split you will be better off using .match here using this regex:
\{\{#a}}.*?\{\{\/a}}/g
This matches {{#a}} followed by 0 or of any character followed by {{/a}}.
or else you may use this more strict regex match:
\{\{#a}}\[[^\]]*]\([^)]*\)\{\{\/a}}
Here:
\[[^\]]*]: Matches [...] substring
\([^)]*\): Matches (...) substring
RegEx Demo
var string = "By signing in, I agree to the {{#a}}[Terms of Use](https://www.example.com/termsofuse){{/a}} and {{#a}}[Privacy Policy](https://www.example.com/privacy){{/a}}.";
console.log( string.match(/\{\{#a}}.*?\{\{\/a}}/g) );
I have a sample format for which I want the regular expression in javascript. The format is as below.
I-KA-BGLK-ENB-V001
I am unable to try as I dont know much about the Regex Please let me know how to get it.
Even If I get the regex it will do, the javascript part I can handle it.
try this
var str = 'I-KA-BGLK-ENB-V001';
var re = /^[A-Z]-[A-Z]{2}-[A-Z]{4}-[A-Z]{3}-[A-Z]\d{3}$/;
re.test(str);// true
[A-Z] - means any uppercase letter
\d - means any digit 0-9
\d{3} - means 3 digits
[A-Z]{2} - means 2 uppercace letters
You can change if you need digits in some places.
If you dont care about lowercase or uppercase replace [A-Z] with \w
https://github.com/zeeshanu/learn-regex - lessons
Or you google "learn regex easy"
The valid regular expression for this is:
^\w-\w{2}-\w{4}-\w{3}-\w{4}$
^\w-\w{2}-\w{4}-\w{3}-\w\d{3}$
Explanation
Code
I don't wanna spoon-feed you, but the next step is to Check whether a string matches a regex in JS.
Well to match strings in the I-KA-BGLK-ENB-V001 format you can use this regex:
^[A-Z]\-[A-Z]{2}\-[A-Z]{4}\-[A-Z]{3}\-\w{4}$
You can test it in Regex101, where you can see an example of matching strings and check the meaning and the specifications for each part of it.
Happy Saturday,
I'm wondering if Stackoverflow's users could give me a clue about one specific Regex..
(^visite\d+)(?!\D)
The above regex works well..
It says that :
visite12345 --> is a good anwser (the string does match)
visite1a --> is not a good anwser (the string doesn't match)
However for:
visite12345a --> It doesn't work.
Indeed, the output is visite1234, whereas I'd like to get the same answer that for visite1a (string doesn't match)...
I use http://regexr.com/ to test my regexp.
Do you have any idea how to so?
Thank you very much.
The regex (^visite\d+)(?!\D) matches visite at the start of the string, followed with one or more digits that should not be followed with a non-digit.
The "issue" is that the engine can backtrack within \d+ pattern and it can match 2 digits if the third is not followed with a nondigit.
The best way to solve it is to check the actual requirements and adjust the pattern.
If the digits are the last characters in the string you just should replace the lookahead with the $ anchor.
A generic solution for this is making the subpattern atomic with a capturing group inside a positive lookahead and a backreference, and make sure the lookahead is changed to something like (?![a-zA-Z]) - fail if there is a letter):
/^visite(?=(\d+))\1(?![a-z])/i
See the regex demo
Or if a word boundary should follow the digits (i.e. digits should be followed with a letter, digit or an underscore), use \b instead of the lookahead:
/^visite\d+\b/
See another demo
/test-test-test/test.aspx
Hi there,
I am having a bit difficult to retrieve the first bit out from the the above URL.
test-test-test
I tried this /[\w+|-]/g but it match the last test.aspx as well.
Please help out.
Thanks
One way of doing it is using the Dom Parser as stated here: https://stackoverflow.com/a/13465791/970247.
Then you could access to the segments of the url using for example: myURL.segments; // = Array = ['test-test-test', 'test.aspx']
You need to use a positive lookahead assertion. | inside a character class would match a literal | symbol. It won't act like an alternation operator. So i suggest you to remove that.
[\w-]+(?=\/)
(?=\/) called positive lookahead assertion which asserts that the match must be followed by an forward slash. In our case test-test-test only followed by a forward slash, so it got matched. [\w-]+ matches one or more word character or hyphen. + repeats the previous token one or more times.
Example:
> "/test-test-test/test.aspx".match(/[\w-]+(?=\/)/g)
[ 'test-test-test' ]
[\w+|-] is wrong, should be [\w-]+. "A series of characters that are either word characters or hyphens", not "a single character that is a word character, a plus, a pipe, or a hyphen".
The g flag means global match, so naturally all matches will be found instead of just the first one. So you should remove that.
> '/test-test-test/test.aspx'.match(/[\w-]+/)
< ["test-test-test"]