Javascript：正则表达式中的空字符串匹配

Question

i want to match the url with contatin http/https and (www) or without (www) with the help of regular expression. following is my regualr expression

^((https?)://)(www\\.)| ^$ +(\.[a-z0-9-]+)+([/?].*)?$

but in this, the empty string is not work for example : when i enter http://www.google.com is valid url but http://google.com is not valid. thanks for the answer in advance.

Answer 1

You can't search for an not existing part using ^$ . that is expecting a start of a string(row), end of the string (row).

Just make the "www" part optional:

^((https?)://)(www\\.)?(\.[a-z0-9-]+)+([/?].*)?$

another problem is, you are searching for two dots in a row:

^((https?)://)(www\\.)?(\.[a-z0-9-]+)+([/?].*)?$
                    ^    ^

I think a better pattern would be

^((https?)://)(www\\.)?([a-z0-9-]+)(\.[a-z0-9-]+)*([/?].*)?$

Are you aware, that you are excluding a lot of valid URLS, by only allowing the characters [a-z0-9-] ?