wp_oembed_add_host_js()

This function is no longer used directly. For back-compat it exists exclusively as a way to indicate that the oEmbed host JS <em>should</em> be added. In default-filters.php there remains this code: add_action( 'wp_head', 'wp_oembed_add_host_js' ) Historically a site has been able to disable adding the oEmbed host script by doing: remove_action( 'wp_head', 'wp_oembed_add_host_js' ) In order to ensure that such code still works as expected, this function remains. There is now a has_action() check in wp_maybe_enqueue_oembed_host_js() to see if wp_oembed_add_host_js() has not been unhooked from running at the wp_head action.