Jupyter notebook: Widget Javascript not detected

Question

Question: I installed python3 and jupyter notebook using pip3 in MacOs 10.9.
When I try to run the widget it gives error that there is no javascript widget. I have python3 and R kernels installed in Jupyter-notebook.

Code:

from ipywidgets import widgets
from IPython.display import display
text = widgets.Text()
display(text)
text.on_submit('hello')

Error:

Widget Javascript not detected.  It may not be installed or enabled properly.  

Attempts:

sudo -H pip3 install ipywidgets  
sudo -H pip3 install -upgrade ipywidgets  
jupyter nbextension enable --py widgetsnbextension
# restarted the computer. 

The last command gives error.

[EnableNBExtensionApp] CRITICAL | Bad config encountered during initialization:
[EnableNBExtensionApp] CRITICAL | Unrecognized flag: '--py'

Note that in mac I have jupyter-nbextension command but the command:

jupyter-nbextension enable --py widgetsnbextension 

does not work either.

But jupyter nbextension enable widgetsnbextension gives no error and also does nothing. The same error is popped in if I run the code.

Also,

import ipywidgets
ipywidgets.__version__

gives '6.0.0'.

Some notes:

which jupyter  
jupyter is /Library/Frameworks/Python.framework/Versions/3.5/bin/jupyter
which jupyter-notebook
jupyter-notebook is /Library/Frameworks/Python.framework/Versions/3.5/bin/jupyter-notebook

Related links:

https://github.com/jupyter-widgets/ipywidgets/issues/541    
https://github.com/jupyter/help/issues/32    
https://github.com/jupyter/help/issues/131    
https://github.com/binder-project/binder/issues/83   

How can I install widgets?
Do I need to install java separately ?

Answer 1

Run the following command: jupyter nbextension enable --py --sys-prefix widgetsnbextension, then restart the kernel in Jupyter should do the trick.