javascript - Regex to allow only a single dot in a textbox

Question

I have one text input.

I wrote a regex for masking all special characters except . and -. Now if by mistake the user enters two . (dots) in input, then with the current regex

var valueTest='225..36'

valueTest.match(/[^-.d]/)

I expected that the number will not pass this condition

How to handle this case. I just want one . (dot) in input field since it is a number.

Answer 1

I think you mean this,

^-?d+(?:.d+)?$

DEMO

It allows positive and negative numbers with or without decimal points.

EXplanation:

• ^ Asserts that we are at the start.
• -? Optional - symbol.
• d+ Matches one or more numbers.
• (?: start of non-capturing group.
• . Matches a literal dot.
• d+ Matches one or more numbers.
• ? Makes the whole non-capturing group as optional.
• $ Asserts that we are at the end.