I have a string where I would like to extract a time stamp. The time stamp could be anywhere in the string, and the timestamp could be different lengths. Think youtube video time stamping.
Here is an example
What would you change for education from your 27:19:45 experience k-12? #change'
I would like to extract 27:19:45. However other strings could contain only MM:SS
The regex I could come up with was
const timeRegex = /(?:(?:([01]?\d|2[0-3]):)?([0-5]?\d):)?([0-5]?\d)/gm;
When I run this regex it also picks up the 12 in the k-12 part of the string which I don't want.
Sorry I removed the seconds part. If it were just seconds it would have 0:12
Use
(?<!\S)(?:(?:(\d{1,2}):)?([0-5]?\d):)?([0-5]?\d)(?!\S)
See regex proof.
In your expression, you need to make MM part compulsory.
EXPLANATION
--------------------------------------------------------------------------------
(?<! look behind to see if there is not:
--------------------------------------------------------------------------------
\S non-whitespace (all but \n, \r, \t, \f,
and " ")
--------------------------------------------------------------------------------
) end of look-behind
--------------------------------------------------------------------------------
(?: group, but do not capture (optional
(matching the most amount possible)):
--------------------------------------------------------------------------------
(?: group, but do not capture (optional
(matching the most amount possible)):
--------------------------------------------------------------------------------
( group and capture to \1:
--------------------------------------------------------------------------------
\d{1,2} digits (0-9) (between 1 and 2 times
(matching the most amount possible))
--------------------------------------------------------------------------------
) end of \1
--------------------------------------------------------------------------------
: ':'
--------------------------------------------------------------------------------
)? end of grouping
--------------------------------------------------------------------------------
( group and capture to \2:
--------------------------------------------------------------------------------
[0-5]? any character of: '0' to '5' (optional
(matching the most amount possible))
--------------------------------------------------------------------------------
\d digits (0-9)
--------------------------------------------------------------------------------
) end of \2
--------------------------------------------------------------------------------
: ':'
--------------------------------------------------------------------------------
)? end of grouping
--------------------------------------------------------------------------------
( group and capture to \3:
--------------------------------------------------------------------------------
[0-5]? any character of: '0' to '5' (optional
(matching the most amount possible))
--------------------------------------------------------------------------------
\d digits (0-9)
--------------------------------------------------------------------------------
) end of \3
--------------------------------------------------------------------------------
(?! look ahead to see if there is not:
--------------------------------------------------------------------------------
\S non-whitespace (all but \n, \r, \t, \f,
and " ")
--------------------------------------------------------------------------------
) end of look-ahead
This one should work:
const timeRegex = /\d\d:\d\d(:\d\d)?/gm
Or, ff the numbers between the colons can be one or two:
const timeRegex = /\d\d?:\d\d?(:\d\d?)?/gm
Test:
s = "What would you change for education from your 27:09:02 experience k-12? #change'"
-> "What would you change for education from your 27:09:02 experience k-12? #change'"
s.match(/\d\d?:\d\d?(:\d\d?)?/gm)
-> ["27:09:02"]
s = "What would you change for education from your 27:09 experience k-12? #change'"
-> "What would you change for education from your 27:09 experience k-12? #change'"
s.match(/\d\d?:\d\d?(:\d\d?)?/gm)
-> ["27:09"]
s = "What would you change for education from your experience k-12? #change'"
-> "What would you change for education from your experience k-12? #change'"
s.match(/\d\d?:\d\d?(:\d\d?)?/gm)
-> null
You can use positive lookahead and positive lookbehind and select only if there is \s on both the side of the time.
const str =
"What would you change for education from your 27:19:45 and 12:12 and 11 experience k-12? #change";
const result = str.match(/(?<=\s)(\d\d:?)+(?=\s)/g);
console.log(result);
Related
I'm trying to get only h1 and h2 headers from markdown file using regex, but unfortunately I don't know regex well and can't write the correct solution.
With this expression I'm near the solution (I think so):
/\#{1,2} (.*?)(\\r\\n|\\r|\\n)/gm
But it returns also headers with more than two hashes.
Test case:
# first \r
## second \r
### third \r## fourth \r
This should return ['first', 'second', 'fourth']
Use
/(?<!#)#{1,2} (.*?)(\\r(?:\\n)?|\\n)/gm
See regex proof.
EXPLANATION
--------------------------------------------------------------------------------
(?<! look behind to see if there is not:
--------------------------------------------------------------------------------
# '#'
--------------------------------------------------------------------------------
) end of look-behind
--------------------------------------------------------------------------------
#{1,2} '#' (between 1 and 2 times (matching the
most amount possible))
--------------------------------------------------------------------------------
' '
--------------------------------------------------------------------------------
( group and capture to \1:
--------------------------------------------------------------------------------
.*? any character except \n (0 or more times
(matching the least amount possible))
--------------------------------------------------------------------------------
) end of \1
--------------------------------------------------------------------------------
( group and capture to \2:
--------------------------------------------------------------------------------
\\ '\'
--------------------------------------------------------------------------------
r 'r'
--------------------------------------------------------------------------------
(?: group, but do not capture (optional
(matching the most amount possible)):
--------------------------------------------------------------------------------
\\ '\'
--------------------------------------------------------------------------------
n 'n'
--------------------------------------------------------------------------------
)? end of grouping
--------------------------------------------------------------------------------
| OR
--------------------------------------------------------------------------------
\\ '\'
--------------------------------------------------------------------------------
n 'n'
--------------------------------------------------------------------------------
) end of \2
I want to limit levels of subdomain to 3 levels only. trying regex below fails
([\.]?[a-z]*){3}
My Target: abc.def.ghi
but
regex above accepts abc.def.ghi. (Notice the last .)
Use
^(?:[a-z]+(?:\.[a-z]+){0,2})?$
See proof.
Explanation
--------------------------------------------------------------------------------
^ the beginning of the string
--------------------------------------------------------------------------------
(?: group, but do not capture (optional
(matching the most amount possible)):
--------------------------------------------------------------------------------
[a-z]+ any character of: 'a' to 'z' (1 or more
times (matching the most amount
possible))
--------------------------------------------------------------------------------
(?: group, but do not capture (between 0 and
2 times (matching the most amount
possible)):
--------------------------------------------------------------------------------
\. '.'
--------------------------------------------------------------------------------
[a-z]+ any character of: 'a' to 'z' (1 or
more times (matching the most amount
possible))
--------------------------------------------------------------------------------
){0,2} end of grouping
--------------------------------------------------------------------------------
)? end of grouping
--------------------------------------------------------------------------------
$ before an optional \n, and the end of the
string
I have a university assignment to write a JS regex for name validation: name can include spaces at the beginning and the end (don't ask anything, it's our teacher demand), also it can include such chars like: -, ' and space (" "). At the moment, my regex looks like that:
var Nameregex = /^( ?)*[A-Z]+((['-])?[a-z]+)*(([ ]?[a-z]*)*)*$/g;
It works almost perfect, but except for one case: one word (words separated from each other with spaces and - symbols) can contain only one ' symbol.
For example, names like John-andrew'andrew'john shouldn't work. But John-andrew'john-andrew'john should work.
Add a (?!.*'[A-Za-z]+') negative lookahead after ^:
/^(?!.*'[A-Za-z]+')\s*[A-Z]+(?:['-]?[a-z]+)*(?:\s*[a-z]*)*$/
See proof
Explanation
--------------------------------------------------------------------------------
^ the beginning of the string
--------------------------------------------------------------------------------
(?! look ahead to see if there is not:
--------------------------------------------------------------------------------
.* any character except \n (0 or more times
(matching the most amount possible))
--------------------------------------------------------------------------------
' '\''
--------------------------------------------------------------------------------
[A-Za-z]+ any character of: 'A' to 'Z', 'a' to 'z'
(1 or more times (matching the most
amount possible))
--------------------------------------------------------------------------------
' '\''
--------------------------------------------------------------------------------
) end of look-ahead
--------------------------------------------------------------------------------
\s* whitespace (\n, \r, \t, \f, and " ") (0 or
more times (matching the most amount
possible))
--------------------------------------------------------------------------------
[A-Z]+ any character of: 'A' to 'Z' (1 or more
times (matching the most amount possible))
--------------------------------------------------------------------------------
(?: group, but do not capture (0 or more times
(matching the most amount possible)):
--------------------------------------------------------------------------------
['-]? any character of: ''', '-' (optional
(matching the most amount possible))
--------------------------------------------------------------------------------
[a-z]+ any character of: 'a' to 'z' (1 or more
times (matching the most amount
possible))
--------------------------------------------------------------------------------
)* end of grouping
--------------------------------------------------------------------------------
(?: group, but do not capture (0 or more times
(matching the most amount possible)):
--------------------------------------------------------------------------------
\s* whitespace (\n, \r, \t, \f, and " ") (0
or more times (matching the most amount
possible))
--------------------------------------------------------------------------------
[a-z]* any character of: 'a' to 'z' (0 or more
times (matching the most amount
possible))
--------------------------------------------------------------------------------
)* end of grouping
--------------------------------------------------------------------------------
$ before an optional \n, and the end of the
string
I want to remove symbols in phone numbers. Sometimes it is in the format of 151-454-6545 but sometimes it is in (545)-(564)-(5465) and in sometimes it is in 548.445.8454. I am using
val.replace(/(\d{3})(\d{3})(\d{4})/, '($1) -$2-$3')
for replacing.. but it doesn't remove the dot.What to do remove the dot also? expected output like 545-455-4545
I suggest to use a non-digit expression to replace them by '-' string :
val.replace(/^\D+/, '')
.replace(/\D+$/, '')
.replace(/\D+/g, '-')
Let me know if it does what you need.
EDIT : trim whitespaces
here is a version with only 1 regex
https://regex101.com/r/Wavw45/1
regex
[^\d\n]*(\d{3})[^\d\n]+(\d{3,4})[^\d\n]+(\d{4})[^\d\n]*
replace (or whatever pattern you want)
($1) -$2-$3
Use
.replace(/^\D*(\d{3})\D*(\d{3})\D*(\d{4})\D*$/, '$1-$2-$3')
See proof.
Explanation
--------------------------------------------------------------------------------
^ the beginning of the string
--------------------------------------------------------------------------------
\D* non-digits (all but 0-9) (0 or more times
(matching the most amount possible))
--------------------------------------------------------------------------------
( group and capture to \1:
--------------------------------------------------------------------------------
\d{3} digits (0-9) (3 times)
--------------------------------------------------------------------------------
) end of \1
--------------------------------------------------------------------------------
\D* non-digits (all but 0-9) (0 or more times
(matching the most amount possible))
--------------------------------------------------------------------------------
( group and capture to \2:
--------------------------------------------------------------------------------
\d{3} digits (0-9) (3 times)
--------------------------------------------------------------------------------
) end of \2
--------------------------------------------------------------------------------
\D* non-digits (all but 0-9) (0 or more times
(matching the most amount possible))
--------------------------------------------------------------------------------
( group and capture to \3:
--------------------------------------------------------------------------------
\d{4} digits (0-9) (4 times)
--------------------------------------------------------------------------------
) end of \3
--------------------------------------------------------------------------------
\D* non-digits (all but 0-9) (0 or more times
(matching the most amount possible))
--------------------------------------------------------------------------------
$ before an optional \n, and the end of the
string
I am attempting to validate text input with the following requirements:
allowed characters & length /^\w{8,15}$/
must contain /[a-z]+/
must contain /[A-Z]+/
must contain /[0-9]+/
must not contain repeated characters (ie. aba=pass and aab=fail)
Each test would return true when used with .test().
With modest familiarity, I am able to write the first 4 tests, albeit individually. The 5th test is not working out, negated lookahead (which is what i believe i need to be using) is challenging.
Here are a few value/result examples:
re.test("Fail1");//returns false, too short
re.test("StringFailsRule1");//returns false, too long
re.test("Fail!");//returns false, invalid !
re.test("FAILRULE2");//returns false, missing [a-z]+
re.test("failrule3");//returns false, missing [A-Z]+
re.test("failRuleFour");//returns false, missing [0-9]+
re.test("failRule55");//returns false, repeat of "5"
re.test("TestValue1");//returns true
Finally, the ideal would be a single combined test used to enforce all requirements.
This uses negative and positive lookaheads zero-length assertions for your tests and the .{8,15} bit validates length.
^(?!.*(.)\1)(?=.*[a-z])(?=.*[A-Z])(?=.*[0-9])\w{8,15}$
For your fifth rule I used a negative lookahead to make sure that a capture group of any character is never followed by itself.
Regexpal demo
NODE EXPLANATION
--------------------------------------------------------------------------------
^ the beginning of the string
--------------------------------------------------------------------------------
(?! look ahead to see if there is not:
--------------------------------------------------------------------------------
.* any character except \n (0 or more times
(matching the most amount possible))
--------------------------------------------------------------------------------
( group and capture to \1:
--------------------------------------------------------------------------------
. any character except \n
--------------------------------------------------------------------------------
) end of \1
--------------------------------------------------------------------------------
\1 what was matched by capture \1
--------------------------------------------------------------------------------
) end of look-ahead
--------------------------------------------------------------------------------
(?= look ahead to see if there is:
--------------------------------------------------------------------------------
.* any character except \n (0 or more times
(matching the most amount possible))
--------------------------------------------------------------------------------
[a-z] any character of: 'a' to 'z'
--------------------------------------------------------------------------------
) end of look-ahead
--------------------------------------------------------------------------------
(?= look ahead to see if there is:
--------------------------------------------------------------------------------
.* any character except \n (0 or more times
(matching the most amount possible))
--------------------------------------------------------------------------------
[A-Z] any character of: 'A' to 'Z'
--------------------------------------------------------------------------------
) end of look-ahead
--------------------------------------------------------------------------------
(?= look ahead to see if there is:
--------------------------------------------------------------------------------
.* any character except \n (0 or more times
(matching the most amount possible))
--------------------------------------------------------------------------------
[0-9] any character of: '0' to '9'
--------------------------------------------------------------------------------
) end of look-ahead
--------------------------------------------------------------------------------
\w{8,15} word characters (a-z, A-Z, 0-9, _)
(between 8 and 15 times (matching the most
amount possible))
--------------------------------------------------------------------------------
$ before an optional \n, and the end of the
string