1. A method of performing persistent processing on behalf of applications within a virtual environment of a device having a processor, the method comprising: executing, on the processor, instructions that cause the device to: responsive to a request from an application hosted in a web page to execute a worker process involving an execution event, initiate execution of the worker process outside of the virtual environment; responsive to termination of the web page, refrain from terminating the worker process; and responsive to an instance of the execution event, transmit a message from the worker process to the application to notify the application of the instance of the execution event handled by the worker process.