wp-includes/class-wp-editor.php:1051Returns the TinyMCE base URL.
string public static function get_baseurl() { if ( empty( self::$baseurl ) ) { self::$baseurl = includes_url( 'js/tinymce' ); } return self::$baseurl; }Introduced in 4.8.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/class-wp-editor.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.