WordPress at a glance
function is not described

rest_get_url_prefix() WP 4.4.0

Retrieves the URL prefix for any API resource.

Hooks in function
Return

String. Prefix.

Usage

rest_get_url_prefix();

Code of rest get url prefix: wp-includes/rest-api.php VER 5.0.3

<?php
function rest_get_url_prefix() {
	/**
	 * Filters the REST URL prefix.
	 *
	 * @since 4.4.0
	 *
	 * @param string $prefix URL prefix. Default 'wp-json'.
	 */
	return apply_filters( 'rest_url_prefix', 'wp-json' );
}