Javacsript Regular Expression matches number with maximum 10 digits with optional 2 decimal points-CodePudding

I have tried below regular expression to validate the number with following criteria

/^\d{3,10}(\.\d{2})?$/

a, number should be minimum 3 , maximum 10 (including .) digits and it may contain . and two decimal point

Examples

valid numbers

123

1234

12345

123456

1234567

12345678

123456789

1234567890

123.00

1234.02

12345.03

123456.04

1234567.05

Invalid numbers

1.11

1.1111

12345678.12

But my regex fail in case of 1234567890.00

CodePudding user response：

You can use:

^(?![.\d]{11,}$)\d{3,10}(?:\.\d\d)?$

Explanation

^ Start of string
(?![.\d]{11}$) Negative lookahead, assert not 11 or more digits or dots till the end of the string
\d{3,10} Match 3-10 digits
(?:\.\d\d)? Optionally match . and 2 digits
$ End of string

See a regex demo.

CodePudding user response：

I see a contradiction in your description of 3 to 10 digits including ., and your invalid example 1.11, which has 3 chars (digits and .)

Here is a regex with tests assuming you want to test for 3 to 10 chars (digits and .) :

const input = [
  '123',
  '1234',
  '12345',
  '123456',
  '1234567',
  '12345678',
  '123456789',
  '1234567890',
  '1.23',
  '123.00',
  '1234.02',
  '12345.03',
  '123456.04',
  '1234567.05',
  '1',
  '12',
  '1.1111',
  '1.22.33',
  '12345678.12',
  '1234567890.00'
];
const regex = /^(?=.{3,10}$)\d (\.\d{2})?$/;
input.forEach(str => {
  let valid = regex.test(str);
  console.log(str   ' => '   valid);
});

Output:

123 => true
1234 => true
12345 => true
123456 => true
1234567 => true
12345678 => true
123456789 => true
1234567890 => true
1.23 => true
123.00 => true
1234.02 => true
12345.03 => true
123456.04 => true
1234567.05 => true
1 => false
12 => false
1.1111 => false
1.22.33 => false
12345678.12 => false
1234567890.00 => false

Explanation of regex:

^ -- start of string
(?=.{3,10}$) -- positive lookahead asserting 3 to 10 chars
\d -- 1 chars
(\.\d{2})? -- optional .nn pattern
$ -- end of string