This test displays the automatic type conversion for data that is sent from the backend to the frontend.

All values you enter into that form are simply bounced back by the CPAINT backend, nothing is done with them.
The CPAINT frontend performs a type conversion on a by-value basis. So if a value is a valid integer or floating point number, it will convert it to a JavaScript number automatically for you.

This test displays this for you by adding the number 42 to the value that is returned: For numbers the values are added (1 + 42 == 43), for string values they are concatenated (one + 42 == one42).