WordPress at a glance
function is not described

WP_REST_Request::get_param() public WP 4.4.0

Retrieves a parameter from the request.

{} It's a method of the class: WP_REST_Request{}

No Hooks.

Return

Mixed/null. Value if set, null otherwise.

Usage

$WP_REST_Request = new WP_REST_Request();
$WP_REST_Request->get_param( $key );
$key(string) (required)
Parameter name.

Changelog

Since 4.4.0 Introduced.

Code of WP_REST_Request::get_param() WP 5.5.1

<?php
public function get_param( $key ) {
	$order = $this->get_parameter_order();

	foreach ( $order as $type ) {
		// Determine if we have the parameter for this type.
		if ( isset( $this->params[ $type ][ $key ] ) ) {
			return $this->params[ $type ][ $key ];
		}
	}

	return null;
}