What protocol is loaded when using protocol-relative URLs?

Question

I just started to test the idea behind "protocol less Urls".

The problem I´m looking to solve is: on a https page I need to load an external css file from http.

Doing this the "normal" way results in failure... the css file is blocked. (Just testing with chrome for now).

So my question is: Will "protocol less Urls" load the file from http/https/both?

Not sure but you can check [this answer](http://stackoverflow.com/questions/3292697/find-out-what-resources-are-not-going-over-https). — The Alpha, Aug 22 '12 at 08:41
This seems to show up #1 in Google. See http://stackoverflow.com/questions/4831741/can-i-change-all-my-http-links-to-just for detailed answer — epascarello, Dec 30 '14 at 21:11
btw, protocol-relative URL is now an anti-pattern : http://www.paulirish.com/2010/the-protocol-relative-url/ — user, Jan 19 '16 at 16:34

score 13 · Accepted Answer · edited May 23 '17 at 12:22

13

If you're referring to URLs like www.example.com/style.css, that won't work because the protocol is completely missing; a browser will treat www.example.com as some kind of directory path name.

If you're referring to URLs like //www.example.com/style.css, that is a protocol-relative URL; it uses the same protocol as what the browser is already using to request the referring page. For example, if the browser had requested a page with https://www.example.com, then that URL will be requested over HTTPS and not HTTP.

Browser support for these URLs is generally pretty good; see the following questions:

edited May 23 '17 at 12:22

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answered Aug 22 '12 at 08:43

BoltClock

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So it will inherit the current protocol... so on my https page it will try to load the css from https? – Mackelito Aug 22 '12 at 08:44
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That's correct. Your server just needs to be able to respond appropriately. – BoltClock Aug 22 '12 at 08:44
Hmm.. so is there some way to work around this? The second server does not have https – Mackelito Aug 22 '12 at 08:47
Why does the second server block if you try using `http://`? It sounds like something was misconfigured... – BoltClock Aug 22 '12 at 08:48
It´s not blocked by server but by the browser (chrome in this case) – Mackelito Aug 22 '12 at 08:49
does it work for loading css file in another css file using import rule? – Krunal Mar 26 '14 at 05:08
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@Krunal: It should work. – BoltClock Mar 26 '14 at 06:46
@BoltClock Thanks for notifying. I did checked this already and it worked great. +1 – Krunal Mar 26 '14 at 11:36

What protocol is loaded when using protocol-relative URLs?

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