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Regex for only positive decimals from 0 to 1 upto 2 decimal digits only that works without sign in JavaScript? [duplicate]

This question already has answers here:
Regex decimal values between 0 and 1 up to 4 decimal places
(2 answers)
Closed 2 years ago.
I basically want a regex for alpha in RGBA which is always a positive number between 0 & 1. However, I want it to only be upto 2 digits like 0.53 & not more than that like 0.536.
Allowed
Anything between 0 to 1 but only upto 2 decimal places
0
0.0
0.00
0.1
0.12
0.34
1
1.0
1.00
Not Allowed
Anything outside of 0 to 1 & if its between 0 to 1 then it should be less than or equal to 2 decimal places only & even signs not allowed
0.123
90
3
-1
+1
I noticed other similar questions but they allow signs or they allow more than 2 decimal places.
Currently, I have a regex like /^(0+\.?|0*\.\d+|0*1(\.0*)?)$/ which allows for more than 2 decimal places. How do I solve it?

You may use:
^(?:0(?:\.[0-9]{1,2})?|1(?:\.00?)?)$
RegEx Demo
RegEx Details:
^: Start
(?:: Start a non-capture group
0: Match 0
(?:\.[0-9]{1,2})?: Match optional dot followed by 1 or 2 digits
|: OR
1: Match 1
(?:\.00?)?: Match optional 1 or 2 zeroes after dot
): End non-capture group
$: End

Alternatively, try:
^(?!1..?[1-9])[01](?:\.\d\d?)?$
See the online demo
^ - Start string anchor.
(?! - Open negative lookahead:
1..? - A literal "1" followed by any character other than newline and an optional one.
[1-9]- Match a digit ranging from 1-9.
) - Close negative lookahead.
[01] - Match a zero or one.
(?: - Open non-capture group:
\.\d\d? - Match a literal dot, a single digit and an optional one.
)? - Close non-capturing group and make it optional.
$ - End string anchor.

Allow integers from 0 to 59 after ':' in a string [duplicate]

I am trying to validate minutes:seconds input where minutes can be 07 or 7.
I can get 07:35 validated using below but not 7:35. When I process the input I can append a zero if values is less than 9 but want to be able to let users type 7:35 as well.
^([0-5]\d:[0-5]\d$)

You may make the first munite digit optional:
^[0-5]?\d:[0-5]\d$
^
See the regex demo
Details
^ - start of string
[0-5]? - an optional (1 or 0 repetitions) of a 0 to 5 digit
\d - any 1 digit
: - a : char
[0-5] - a digit from 0 to 5
\d - any 1 digit
$ - end of string.

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}$

Regex for a number which can starts with 0

I use this regex for my field:
/^([1-9]([0-9]){0,3}?)((\.|\,)\d{1,2})?$/;
What I want to do is to allow the user to enter 0 as a beginning of the number, but in this cas, he must enter at least a second digit diffrent from 0 and the same rule is applied for the third and fourth digits.
Example:
01 -> valid
00 -> not valid
0 -> not valid
1 -> valid
In short, zero value must not be allowed. How can I do this using Regex? or would it be better if I just do it with a javascript script?

If you want to only match numbers that have 1 to 4 digits in the part before a decimal separator, and up to 2 digits after the decimal separator (I deduce it from the regex you used) and that do not start with 00 (that requirement comes from your verbal explanation), use
/^(?!00)(?!0+(?:[.,]0+)?$)\d{1,~4}(?:[.,]\d{1,2})?$/
See the regex demo.
Details
^- start of string
(?!00) - no two 0s at the start of the string
(?!0+(?:[.,]0+)?$) - a negative lookahead that fails the match if there are one or more 0s, followed with an optional sequence of . or , followed with one or more zeros up to the string end
\d{1,4} - any 1 to 4 digits
(?:[.,]\d{1,2})? - 1 or 0 occurrences of
[.,] - a . or ,
\d{1,2} - any 1 or 2 digits
$ - end of string.
JS demo:
var ss = ['1','1.1','01','01.3','023.45','0','00','0.0','0.00','0001'];
var rx = /^(?!00)(?!0+(?:[.,]0+)?$)\d{1,4}(?:[.,]\d{1,2})?$/;
for (var s of ss) {
var result = rx.test(s);
console.log(s, "=>", result);
}

Try combining JS and RegEx:
if (parseInt(value) != 0 && value.test(/\d+([,.]\d{1,2})?/)) {
//valid
}

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