Develop Reference

regex for age with 2 decimal points

What is regex for age with 2 decimal points value with max value 99.11
Valid examples:
1
12.01
16.06
20.11
Invalid examples:
.0
1.12 (decimal value should be <12)
1.13 (decimal value should be <12)
12.111
100.00 (2 digit before decimal point, max 99.11)
I have tried ^[0-9]\d{0,1}(\.\d[0-1]\d{0,1})*(,\d+)?$ regex but it is not following all criteria.
can anyone help me?

You can try with this pattern:
/^\d{1,2}(\.(0[0-9]|1[01]))?$/
var pattern = /^\d{1,2}(\.(0[0-9]|1[01]))?$/;
console.log(pattern.test('1'));
console.log(pattern.test('12.01'));
console.log(pattern.test('16.06'));
console.log(pattern.test('20.11'));
console.log(pattern.test('.0'));
console.log(pattern.test('1.12'));
console.log(pattern.test('1.13'));
console.log(pattern.test('12.111'));
console.log(pattern.test('100.00'));

Try this.
/^\d\d?(\.(0\d|1[01]))?$/
Description:
^\d\d? - from the start of the string, match 1 or 2 numbers
After that/those numbers, optionally match . plus 2 numbers
The two numbers must be 0 and any number, else 1 and 0 or 1
Anchor to the end of the string

You are missing the two different patterns of floating part, which must be handled with a |.
A character-optimal solution is ^\d{1,2}(\.[0]\d|\.1[01])?$.

RegEx for a number that must contain a decimal point

I am trying to write a regex to validate a decimal number.
The number MUST contain a decimal point.
There must be one digit [0-9] to the right of the decimal point.
There may be max 5 digits to the left of the decimal point but they cannot start with zero unless a zero on its own.
Allowed:
0.1 (first digit can only be zero if followed by the decimal place)
10345.0 (max 5 digits to left of decimal place, there must be 1 digit to right of decimal place)
Not allowed:
0 (no decimal place)
10 (no decimal place)
(no number to the right of the decimal place)
. (no number on either side of the decimal place)
.1 (no number to the left of the decimal place)
This regex validates what comes before the decimal place
^(?:[1-9][0-9]{0,4}|0)$
This regex validates what comes after the decimal place
^[0-9]{1}+$
I just don't know how to combined the two such that the decimal place is mandatory.
How do I solve this problem?

To the best of my knowledge, this works
^(?:[1-9]\d{0,4}|0)\.\d$
Expanded
^ # BOS
(?:
[1-9] \d{0,4} # 1-5 digits, must not start with 0
| # or,
0 # 0
)
\. \d # decimal point and 1 digit
$ # EOS

This RegEx might validate your inputs:
^(\d{1,5}\.\d{1,})$
and you can simply call it using $1.

That should work
const r = /^(?:[1-9]\d{0,4}|0)\.\d+/
const arr = ['0', '1', '1.2', '1.', '1.123', '0123.1', '123.123', '1234.1', '12345.12345678', '123456.123', '0.12'];
arr.forEach((val) => {
console.log(val, r.test(val));
})

Regular expression for length limit 10 digit before decimal till 2 decimal place with Number only?

i want a regular expression for length limit 10 digit with 2 decimal place numbers with only numbers allowed.10 digit before decimal
allowed
1
1111111111
111
1111111111.22
.2
1.2
1.22
Not allowed
4.
.
-1
abc
Null
Emptystring
""
1.222
-1.22
111111111111
tried but not working
^[0-9]*(\.[0-9]{0,2})?$

You're almost there - all you have to do is include a check that the string is not empty (which can be accomplished with a positive lookahead for .{1,10} right after the ^), and check that its first digit string has at most 10 characters (just use a {0,10} quantifier for the digits). Also note that [0-9] simplifies to \d.
In order to also exclude trailing dots, repeat the digit after the dot with {1,2} instead of {0,2}:
^(?!$)\d{0,10}(?:\.\d{1,2})?$
https://regex101.com/r/Ah8dNu/5

I have also prepared below RegEx.
Seems this will also work.
^[0-9]{1,10}((\.)[0-9]{0,2}){0,1}$

javascript regex trailing zeros

Javascript regex
I have following regex, i want to un-match zeros after decimal, 1.0 or 1.00 should not match but should match 1.25 or 1.2
^(?!0\.)(?:\d{1,3}(?:,\d{3})+|\d+)(?:\.\d{1,2})?$
it accepts following inputs
1.00
1.25
does not accept leading zero ex. 0.25
100
1000
1,000
100,000

You need to add a negative lookahead at the end:
^(?!0\.)(?:\d{1,3}(?:,\d{3})+|\d+)(?:\.(?!0+$)\d{1,2})?$
^^^^^^^
See the regex demo
The (?!0+$) negative lookahead restricts the subsequent consuming subpattern \d{1,2})?$ so that the \d{1,2} cannot match 00 or 0 any longer.

This looks at it from the opposite approach at what is allowed instead of excluded:
^[1-9],?[0-9]*.?[1-9]*$

Max 3 digits, up to 3 decimals

It seems I'm stuck again with a simple regex.
What I'd like:
A number between 1 and 999
Optional: a comma , sign
If the comma sign is entered, minimum 1 decimal and maximum 3
decimals should be presebt.
Allowed:
100
999,0
999,999
999,99
Disallowed:
-1
0
999,
999,9999
This is what I have so far:
^[0-9]{1,3}(?:\,[0-9]{1,3})?$
Any tips?

You can use this regex:
/^[1-9]\d{0,2}(?:\,\d{1,3})?$/
RegEx Demo
Main difference from OP's regex is use of [1-9] which matches digits 1 to 9 before rest of the regex.

This regex should work :
^[1-9]\d{0,2}(?:,\d{1,3})?$
Here is the explanation :
^[1-9]: It should begin with a number between 1 and 9
\d{0,2}: Followed by minimum 0, maximum 2 digits (0-9)
(?:,: Followed by a comma
\d{1,3})?: IF there is a comma it should be followed by one to three digits
$: End of line
EXAMPLE
Thanks #dev-null for this link: Explanation