CodeIgniter中的图像文件，CSS和JS文件

Question

I started to work with CodeIgniter today! So i got 2 simple questions!

Question 1 There is any way to automate the way to reference images in php code, instead to writing img/mainpage/folder.png everytime?
Can i set a global variable with path of img files and use this in all pages? Example: set $IMGPATH = '..\img\'. And use something like <img src='$IMGPATH\myimage.png' in all pages?

Question 2 There is any way to load my JS and CSS files just one time and let it avaliable for all pages instead to stay loading JS and CSS files on every page header?
How can i optimze my CSS and JS files using CodeIgniter and load it ONE TIME and let it avaliable for all pages?

Answer 1

Question 1:

You can create a class with static member that will hold the path.

class Path {
  public static $path = "path/to/directory";
}

Then in your code you can call <img src='<?=Path::$path?>/myimage.png' />

Question 2:

It would be possible using frames, but that's really bad idea. Better approach is using caching. If you use apache, you can enable mod_expires and then use something like this:

<IfModule mod_expires.c>
  ExpiresActive On 
  ExpiresByType text/css "access plus 1 week"
  ExpiresByType text/javascript "access plus 1 week"
</IfModule>

This means that the browser will load css and javascript files from internet only once and then it will load them from cache (which is extremely fast) for a week. After the week it will load them again from internet and so on.