A regex that validates a web address and matches an empty string?

Question

The current expression validates a web address (HTTP), how do I change it so that an empty string also matches?

(http|https):\\/\\/[\\w\\-_]+(\\.[\\w\\-_]+)+         


        

Answer 1

Put the whole expression in parenthesis and mark it as optional (“?” quantifier, no or one repetition):

((http|https):\/\/[\w\-_]+(\.[\w\-_]+)+([\w\-\.,@?^=%&:/~\+#]*[\w\-\@?^=%&/~\+#])?)?