Writing scripts in the Tilda designer

The task was set and fulfilled, which consisted in the dynamic change of the value of the goods in the basket, depending on the choice of the method of payment with the subsequent transfer of the already changed order data to the payment system. The difficulty was that Tilda closed its backend, through which it would be possible to carry out the transmission of parameters and had to look for a crossroads, consisting in "sustaining" the values that the server was accepted by the designer, using the JS script.