How is the data from the Server Object transferred to the Client JavaScript Object?

I've created a custom Web Server Control that implements the IScriptControl Interface. I am seeking information about how the data (the properties) from the Server Object is transferred to the client JavaScript Object.
I want to add implementation to the JavaScript Object so that it is able to execute additional, dynamically supplied Ajax/JavaScript methods. These Ajax/JavaScript methods will be dynamically supplied to the Server Object which, in turn, will make them available to the JavaScript Object using Properties. I will probably be using the JavaScript eval() method to execute the dynamic JavaScript but first I want to ensure that my JavaScript Object is secured and only executes code that the Server Object has supplied.
In order to ensure that my JavaScript Object is secured I need to understand how the data is transferred from the Server Object to the JavaScript object but I cannot find ...