Port to tensorflow.js - What should be output_node_names?

[emadehsan]

I want to port your model to Tensorflow.js

1. I downloaded the model provided in Cam2Caption project.

2. Installed tensorflowjs for python. And tried to convert the frozen model to web model with

$ tensorflowjs_converter \
    --input_format=tf_frozen_model \
    --output_node_names='' \
    --saved_model_tags=serve \
    /merged_frozen_graph.pb \
    /web_model

But I don't know what to use for output_node_names parameter?
According to docs:

Can you guys please tell what should be the value of output_node_names for your model?