Absolute URLs omitting the protocol (scheme) in order to preserve the one of the current page

html http url web-applications protocol-relative

34,282

Solution 1

is this URL format safe to use for all browsers.

I can't say anything for sure, but you should be able to test it in different browsers.

And is it a standard?

Technically, it is called "network path reference" according to RFC 3986. Here is the scheme for it:

  relative-ref  = relative-part [ "?" query ] [ "#" fragment ]

  relative-part = "//" authority path-abempty
                / path-absolute
                / path-noscheme
                / path-empty

There is a problem though, when used on a <link> or @import, IE7 and IE8 download the file.

Here is a post written by Paul Irish on the subject:

The protocol-relative URL

Solution 2

Yes I believe it is. Paul Irish coined the term Protocol Relative URL.

I'd also point out it's part of the HTML5Boilerplate project which evangelises cross browser compatibility.

Note: there is an edge case in IE6 with google analytics which is mentioned in Paul's article. So it's not perfect.

Solution 3

Should be safe.

Is specified as format to use in Google's HTML/CSS styleguide: EDIT: latest url : https://google.github.io/styleguide/htmlcssguide.xml#Protocol

34,282

Author by

Bozho

Bozhidar Bozhanov - Senior Java developer (CV | Web CV) Creator of: https://logsentinel.com/ (LogSentinel SIEM) https://logsentinel.com/sentineldb (GDPR-compliant, privacy-by-design datastore) http://computoser.com (algorithmic music generation)

Updated on July 08, 2022

Comments

Bozho almost 2 years
I saw the //somepage.com/resource url format. For example:
```
<img src="//remotesite.com/image1.jpg" />
```
The point of this is that if the current page (the page defining the img tag) is using http, then the request to the remote site is made via http. If it is https - it's https. This eliminates browser warnings of not fully encrypted pages.

My question is - is this URL format safe to use for all browsers. And is it a standard?
bg17aw almost 8 years

This is no longer true, see stackoverflow.com/a/37609402/2237601 or here, they now use https://. Also see here why ommiting the protocol scheme might not be a good idea.
Evan Donovan over 7 years

Note that Paul Irish has updated his post to indicate that resources should now always be served over https when it is feasible to do so. See the post linked by @Sarfraz above.
Lukas Liesis over 7 years

Google analytics snippet code uses this scheme, so i bet it's cross browser while this tool is used by many many websites, they would just provide https version otherwise