Productionalize the model

My use case is to serve re-trained BERT model from huggingface transformers in browser to end users
(users will type in an editor in browser and they will see next word recommendations - like gmail auto compose).

Is there any example to productionalize “transformers” model ? I am having trouble with converting .bin file to tensorflow.js or onnx.js.

How to save transformers model to with .pt or .h5 extension?