wp-includes/rest-api/class-wp-rest-request.php:963Checks if a parameter is set.
$offsetstringbool #[ReturnTypeWillChange] public function offsetExists( $offset ) { $order = $this->get_parameter_order(); foreach ( $order as $type ) { if ( isset( $this->params[ $type ][ $offset ] ) ) { return true; } } return false; }Introduced in 4.4.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/rest-api/class-wp-rest-request.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.