如何在Woocommerce的JS函数中调用Process_Payment（$ order_id）？

I am developing custom payment gateway which is iframe javscript based payment. Onclick the place order i need to getthe response and process the payment.

For example

public function payment_fields() {
echo ' <script>
var success = function(response) {
$this->process_payment // php function
}
sendbillinginfoto(requesttoexernalserverfromiframe);
 </script>';
}

public function process_payment( $order_id ) {


                 $order = wc_get_order( $order_id );
 .......
 .......
}