What regex to use in this case - regex

Question

Correct code:
"key1=val1;key2=val2;key3=val3" -- Correct as each pair is having ";" at the end except the last pair
Incorrect code:
"key1=val1;key2=val2; key3=val3;" -- Invalid as last pair is having ";" at the end
"key1=val1;;;key2=val2;;;key3=val3" -- Invalid as there are multiple ";" in the middle
I got the regex below from some old link in stackoverflow, but it is not working in the above case:
^(?:\s*\w+\s*=\s*[^;]*;)+$

Answer 1

You might use
^\w+\s*=\s*\w+(?:;\s*\w+\s*=\s*\w+)*$
Explanation
^ Start of string
\w+\s*=\s*\w+ Match 1+ word chars, = and 1+ word chars with optional whitespace chars
(?: Non capture group
;\s*\w+\s*=\s*\w+ Match ; and the same patter as mentioned above
)* Close the group and repeat 0+ times
$ End of string
Regex demo
With the doubled backslashes
^\\w+\\s*=\\s*\\w+(?:;\\s*\\w+\\s*=\\s*\\w+)*$

Answer 2

Also, a shorter one:
^(?:\s*\w+\s*=\s*\w+(?:;(?!\s*$)|\s*$))+\s*$
See proof
Explanation
EXPLANATION
--------------------------------------------------------------------------------
^ the beginning of the string
--------------------------------------------------------------------------------
(?: group, but do not capture (1 or more times
(matching the most amount possible)):
--------------------------------------------------------------------------------
\s* whitespace (\n, \r, \t, \f, and " ") (0
or more times (matching the most amount
possible))
--------------------------------------------------------------------------------
\w+ word characters (a-z, A-Z, 0-9, _) (1 or
more times (matching the most amount
possible))
--------------------------------------------------------------------------------
\s* whitespace (\n, \r, \t, \f, and " ") (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))
--------------------------------------------------------------------------------
\w+ word characters (a-z, A-Z, 0-9, _) (1 or
more times (matching the most amount
possible))
--------------------------------------------------------------------------------
(?: group, but do not capture:
--------------------------------------------------------------------------------
; ';'
--------------------------------------------------------------------------------
(?! look ahead to see if there is not:
--------------------------------------------------------------------------------
\s* whitespace (\n, \r, \t, \f, and " ")
(0 or more times (matching the most
amount possible))
--------------------------------------------------------------------------------
$ before an optional \n, and the end
of the string
--------------------------------------------------------------------------------
) end of look-ahead
--------------------------------------------------------------------------------
| OR
--------------------------------------------------------------------------------
\s* whitespace (\n, \r, \t, \f, and " ")
(0 or more times (matching the most
amount possible))
--------------------------------------------------------------------------------
$ before an optional \n, and the end of
the string
--------------------------------------------------------------------------------
) end of grouping
--------------------------------------------------------------------------------
)+ end of grouping
--------------------------------------------------------------------------------
\s* whitespace (\n, \r, \t, \f, and " ") (0 or
more times (matching the most amount
possible))
--------------------------------------------------------------------------------
$ before an optional \n, and the end of the
string

Answer 3

Try below:
.*\w;\w.*\w;\w.*[^;]$
Test here
Explanation:
.* --> matches any character
\w --> matches any word character
[^;]$ --> Will exclude any line ending with ;

Answer 4

I find things like this much easier without regex. For eample with JavaScript:
function isValid(string) {
return string.split(/;/).map(e => e.split(/=/)).every(e => e.length === 2);
}