In the context of parent – child themes, be aware that:
The get_template_directory_uri() will give you the parent theme directory uri: https://codex.wordpress.org/Function_Reference/get_template_directory_uri.
The get_stylesheet_directory_uri() will give you the child theme directory uri:
https://codex.wordpress.org/Function_Reference/get_stylesheet_directory_uri
You are enqueueing parent-style with get_stylesheet_directory_uri(), which will give you the child theme directory uri.
You are enqueueing child-css and child-js using get_template_directory_uri, which will give you the parent theme directory uri.
So you might want to use get_template_directory_uri() when enqueueing parent scripts and styles, and get_stylesheet_directory_uri() when enqueueing child theme scripts and styles.
If you want to enqueue from another source (e.g. bootstrap) , just use the url:
wp_enqueue_style( 'your-prefix-bootstrap', 'https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css' );
wp_enqueue_script( 'your-prefix-bootstrap', 'https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js' );