WordPress at a glance
function is not described

wp_oembed_add_host_js() WP 4.4.0

Adds the necessary JavaScript to communicate with the embedded iframes.

No Hooks.

Return

Nothing (null).

Usage

wp_oembed_add_host_js();

Code of wp oembed add host js: wp-includes/embed.php WP 5.2.1

<?php
function wp_oembed_add_host_js() {
	wp_enqueue_script( 'wp-embed' );
}