Where should I put css, js and images in Codeigniter project?

When I start using Codeigniter as a PHP framework, I was confuse about where is the properly place to put assets files such as .css .js or images in to my project.

This is the way I put assets files to Codeigniter project.

1. I create folder name “assets” to ¬†the outer path of my project.

Screen Shot 2014-04-12 at 12.04.52 PM

 

2. I also create any folders such as css, js and images in to “assets” folder.

Screen Shot 2014-04-12 at 12.06.48 PM

 

3. Then I use helper function to help me to use any files in “assets” easily. I create one file name “utility_helper.php” and put it to application->helpers folder then write down the function :

function asset_url(){
   return base_url().'assets/';
}

where base_url() refer to my website path.

4.