URL validation does not recognize URLs with no protocol

[jplaut]

http://w is a valid url, but www.google.com is not. This seems to be a bug.

Working fiddle here: http://jsfiddle.net/HB7LU/2390/

A better regex that recognizes both types of urls can be found here: http://stackoverflow.com/questions/833469/regular-expression-for-url

[auser]

In discussion with @IgorMinar:

Does it make sense that the url is valid without a protocol? For instance, currently http://google.com is a valid url, while google.com is not. Similarly, http://localhost is a valid url, while localhost is not a valid url.

I believe that if localhost were a valid URL, then it would follow suit that foo would be a valid URL and the URL validation would be kind of useless.

I think http://w is a valid url as it is in the same form as http://localhost.

[jplaut]

I don't think that localhost is a valid URL. localhost with a port number, which is how localhost is used 99% of the time (localhost:3000, for example) would be valid. I also think that google.com and www.google.com should be valid. Here's a regex that matches google.com, www.google.com, http://google.com, localhost:3000, but not just a word like localhost.

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

[blaise-io]

I'd prefer TLD's to be required, because in the real world, all websites have a TLD, except for localhost and IP addresses. So maybe adopt the Django URL validator RegExp, which does just that, and is already battle-tested?

[caitp]

No matter what you do, you're always going to find people who have a problem with it. This is why I prefer to go with the bare bones validation provided by the RFC/recommended by the W3C, they can be extended if necessary using pattern validators, but otherwise work very well.