PayPal is a good example of a company that moved from Java to Node.js where the server listens to the client then have it slowly replace code going forward on the back end. [0]

There is a discussion that the bigger issue was getting management to allow them to rebuild all the code and by using Node over Java provided a mechanism to do this. This is touched on in the article.

[0] https://www.paypal-engineering.com/2013/11/22/node-js-at-pay...