RegEx validation of decimal numbers with comma or dot

Question

How to validate such number input with one RegEx. Strings are not allowed. Two decimal positions after dot or comma.

Example:

123.34
1.2

Answer 1

This is my method to test decimals with , or . With two decimal positions after dot or comma.

1. (\d+) : one or more digits
2. (,\d{1,2}|\.\d{1,2})? : use of . or , followed by 2 decimals maximum

const regex = /^(\d+)(,\d{1,2}|\.\d{1,2})?$/;

console.log("0.55 returns " + regex.test('0.55')); //true
console.log("5 returns " + regex.test('5')); //true
console.log("10.5 returns " + regex.test('10.5')); //true
console.log("5425210,50 returns " + regex.test('5425210,50')); //true

console.log("");

console.log("10.555 returns " + regex.test('10.555')); //false
console.log("10, returns " + regex.test('10,')); //false
console.log("10. returns " + regex.test('10.')); //false
console.log("10,5.5 returns " + regex.test('10,5.5')); //false
console.log("10.5.5 returns " + regex.test('10.5.5')); //false

Answer 2

Try This,

/^(\d+(?:[\.\,]\d{1,2})?)$/

Answer 3

pat = re.compile('^\d+([\.,]\d\d)?$')
re.match(pat, '1212')
<_sre.SRE_Match object at 0x91014a0>
re.match(pat, '1212,1231')
None
re.match(pat, '1212,12')
<_sre.SRE_Match object at 0x91015a0>

Answer 4

Try this regex:

/^(\d+(?:[\.\,]\d{2})?)$/

If $1 exactly matches your input string then assume that it is validated.