How to execute javascript from an applescript (Yosemite)?

Since Yosemite, the Script Editor allows using javascript.

What is the best way to execute javascript from an applescript?

My use case is an existing applescript which needs to send some parameters over to a piece of javascript code, which makes a complex calculation and returns a result to be used as part of some appplescript-powered automations.

For clarity, I'm looking for an alternative to a tell application [browser] to execute the javascript using the new native javascript support of Yosemite, NOT for an alternative to a do shell script.