Relative path or url for html src and href attribu

Question

Using a framework makes it easy to list full url's for my html src and href attributes, and I feel I'm being more thorough by listing a full url instead of a relative path. But is this faster? Am I incurring an extra DNS lookup? What is the best practice when the content is on the same server?

<img src='http://site.com/images/img1.png' />

vs

<img src='/images/img1.png' />

Codeigniter's image helper img() works like this from the users' guide:

echo img('images/picture.jpg');
// gives <img src="http://site.com/images/picture.jpg" />

and Codeigniter's anchor helper anchor() works like this from the users guide:

echo anchor('news/local/123','My News');
// gives <a href="http://example.com/index.php/news/local/123" >My News</a>

Answer 1

'Never' (alsmost never) use absolute paths.

It will bite you in the ass later.

For example when you switch / add another domain.

Go from your test to production server.

Basically the rule is internal URL's should be relative.

Answer 2

As far as DNS goes, it really doesn't matter if you have relative or absolute URL. Your browser ends up pre-pending the server URI onto the front anyway. Also, your network stack does the lookup for the first time, and caches the IP. Unless something goes wrong, there should only be the one lookup per page. YMMV of course, but that should be how this all works.

Answer 3

Portability would be the issue for me. I would choose the second option based on that alone.

Answer 4

Oh you really don't want to use a full path. You'll have a lot of work ahead of you:

• If you want to develop the site locally
• You change / add domains (development, staging, etc)
• You switch to using a CDN

You also will break your dev environment, since most modern ones will perform local directory lookups. Can't do that with a domain.

Also, in a dev environment you will be pulling from the production site, which will make modifying and adding images extremely tricky.

Most importantly, other developers working with your code will try to kill you. And that's bad for your health.