1. A computer-implemented system comprising: a JavaScript proxy generator to automatically generate a JavaScript proxy in a form of a Java application programming interface (API), the JavaScript proxy associated with a JavaScript module, wherein the JavaScript proxy generator comprises a JavaScript annotation module to create a definition for the JavaScript module and a scripting engine to generate the JavaScript proxy using the definition; and a runtime module to: call the JavaScript proxy from the Java module; responsive to the calling, pass control of execution to the JavaScript module; execute the JavaScript module to generate an output method or object; and pass control of execution to the Java module to continue execution of the Java module.