带有可选小数点的十进制数的正则表达式

Question

My requirement is to test the pasted data and if it fails then don't paste.

Regex: /\d{0,4}([\.|\,]\d{0,2})?/

Data used:

1.2 tests true
1.2.3 test true as well

Requirement is

min 0 max 4 digits before decimal point
decimal point can be either dot or comma
min 1 max 3 digits after decimal point if there exists a decimal point.

I have tried following but does not work.
Any help will be appreciated.

fiddle

Answer 1

From your requirements

/^\d{0,4}(?:[.,]\d{1,3})?$/

1. ^ : Start of the line
2. \\d{0,4} : Zero-to-four digits
3. [.,] : Match dot or comma
4. \\d{1,3} : One-to-three digits
5. (?: ... ) : Non-capturing group
6. (something)? The group can occur zero or once
7. $ : End of line

 input:valid { color: green; font-weight: bold } input:invalid { color: red; }

 <input type="text" pattern="\\d{0,4}(?:[.,]\\d{1,3})?" />