[koreth1]

I mostly don't work on web stuff, so maybe this is a dumb question, but can you give an example of what benefits that gives you? What code do you want to run in both places?

In my limited experience writing web code, the client side concerns itself with rendering and user interaction, the server side concerns itself with efficiently supplying dynamic data to the client, and other than request payload definitions the two have no logic in common.

[sjwright]

The most straightforward example I can offer is my custom mark-up parser for formatting text. I wrote this parser in Javascript where it runs live in the browser, but when the final text is submitted it's parsed on the server side for security and replicability reasons.

Of course I could rewrite it in another language, but with Nashorn I don't need to. I can execute many hundreds of lines of Javascript with around four lines of utterly boilerplate Java. And it works perfectly. I don't need to worry about edge cases or dealing with subtle variations in regular expressions (don't at me) and other string parsing nuances.

I'm just a sole developer; I don't have minions. If I had to rewrite it today I'd probably look at a transpiling approach, but even then, defensive text manipulation tends to be edge-casey at the best of times.

(Also note that my priority here is browser performance, where it's running continuously on hundreds of clients simultaneously—often budget smartphones with limited CPU power. On the server it only has to run once per submit and the CPU cost on the server is beyond trivial.)

[koreth1]

Makes sense. Thanks for the example!