Browser support for URLs beginning with double slash

Question

I\'ve recently seen a few links used without a protocol. It didn\'t seem too difficult to understand - I think it\'s a great idea and pretty intuitive.

For those of

Answer 1

If you are developing on a local machine there's possibility it will fail with src="file://host.com/filename".

In this situation you need to specify scheme explicitly: http://host.com/filename or https://host.com/filename.

Answer 2

This behavior was part of RFC 1808 (Section 4) which is about 16 years old, so every major browser should (and does) support this.

Sadly, there's a bug with IE7 and -8 that will make them download the resources twice if a protocol-relative URL is used on a link or @import - which shouldn't be a big problem, but is ugly and should be kept in mind.