Regex allow digits and a single dot

Question

What would be the regex to allow digits and a dot? Regarding this \D only allows digits, but it doesn't allow a dot, I need it to allow digits and one dot this is refer as a float value I need to be valid when doing a keyup function in jQuery, but all I need is the regex that only allows what I need it to allow.

This will be in the native of JavaScript replace function to remove non-digits and other symbols (except a dot).

Cheers.

Answer 1

If you want to allow 1 and 1.2:

(?<=^| )\d+(\.\d+)?(?=$| ) 

If you want to allow 1, 1.2 and .1:

(?<=^| )\d+(\.\d+)?(?=$| )|(?<=^| )\.\d+(?=$| ) 

If you want to only allow 1.2 (only floats):

(?<=^| )\d+\.\d+(?=$| ) 

\d allows digits (while \D allows anything but digits).

(?<=^| ) checks that the number is preceded by either a space or the beginning of the string. (?=$| ) makes sure the string is followed by a space or the end of the string. This makes sure the number isn't part of another number or in the middle of words or anything.

Edit: added more options, improved the regexes by adding lookahead- and behinds for making sure the numbers are standalone (i.e. aren't in the middle of words or other numbers.

Answer 2

\d*\.\d* 

Explanation:

\d* - any number of digits

\. - a dot

\d* - more digits.

This will match 123.456, .123, 123., but not 123

If you want the dot to be optional, in most languages (don't know about jquery) you can use

\d*\.?\d*