I wrote the the original machine learning for our company using a fork of brain.js. We launched to 300k+ users the first day with a model training time of under 10 seconds. I&#x27;ve since re-written our machine learning in Go. For getting something out the door quickly, Javascript is great.<p>It worked well for us because we had to stream the data into the network for training, --all the training data did not fit into RAM on Heroku&#x27;s 1G dyno. Node.js does this IO transfer really well. (Full disclosure, I wrote the streaming implementation for brain.js.)<p>Also, training artificial neural networks is a serial computation for the most part. (Lots of sigmas). There are parallel optimizations you can make but probably won&#x27;t see the benefits (in terms of training speed) until you have high dimensional data. Doing this sort of thing on a GPU is also orders of magnitude faster.<p>One thing to note however, if you plan on serving a high number predictions from trained models in Javascript, you will see blocking because each prediction does require a small bit of computation and Javascript &#x2F; Node.js is single threaded.