How to create a Regex expression that accepts an Empty String/ null values?

Question

I am trying to write up a regular expression that accepts numbers, decimals as well as an empty string / null value.

My current expression accepts decimal values that are dot separated. The numbers can start with either a - (minus) or + (plus). Additionally, the value can start with a decimal point - for instance: .56

Here is the expression:

/^([-+]?(\d+|\.\d+|\d+\.\d*))?$/

How can I refactor it to accept an empty string/ null value?

Answer 1

You can write something like this :

/^(?:[-+]?(\d+|.\d+|\d+.\d*))?$/

or maybe just append null using pipe:

/^(?:[-+]?(\d+|.\d+|\d+.\d*))?$/|null