Head-related functions

Up to View-related functions

• auto_discovery_link_tags
• css_src
• head
• head_css
• head_js
• js_escape
• js_tag
• queue_css_file
• queue_css_string
• queue_css_url
• queue_js_file
• queue_js_string
• queue_js_url
• theme_header_background
• theme_header_image
• theme_logo