I want to make a decimal number that is greater than 0 and less than 1, with at most 3 decimal places. So 0, 0.0004, 0.00, 00.004, are NOT valid. But 0.004 is valid.
I thought this shall be simple but couldn't get it working.
This is what I came up with: /^0(?:\.)([1-9]{1,3}?$)/g which makes 0.004 invalid but 0.004 is valid.
You may use this regex with a negative lookahead assertion to disallow all zeroes after dot:
^0\.(?!0+$)\d{1,3}$
RegEx Details:
^: Start0\.: Match 0.(?!0+$): Make sure we don't have all zeroes ahead\d{1,3}: Match 1 to 3 digits$: EndAbove regex uses anchors assuming only one such number per line. If there are multiple decimal numbers per line then use word boundary instead of anchors:
\b0\.(?!0+$)\d{1,3}\b
If trailing 0 is not be allowed after dot then use:
^0\.\d{0,2}[1-9]$
\b0\.\d{0,2}[1-9]\b
While regex tend to be short, they're also cryptic. If you're open to alternatives:
const validate = n => {
n = Number.parseFloat(n) * 1000;
return Number.isInteger(n) && n > 0 && n < 1000;
};
This regular expression should do the trick
^0\.\d{1,3}$
You can test it here