add_style
Add a stylesheet file. The loader class will load all of them when draw the layout.
add_style( "style.css" );
add_script
Add a javascript file.
add_style( "style.css" );
add_javascript
Add javascript code. Loader class add it in the head tag of the layout. If you set onload, the javascript is called when the page is loaded.
add_javascript( "alert('loaded');", $onload = true );