Jupyter：如何从JavaScript回调到函数中的单元格？

Question

my question is about interactive Jupyter notebooks.

I want to display JavaScript button and print something to cell as result of button click.

We can do this easely with ipywidgets:

def OnClick(b=None): print 'qq'
b = widgets.Button(description='Button')
b.on_click(OnClick)
display(b)

But when we jumps to pure JavaScript things goes wrong. Ie I have JavaScript Button, in on_click() event handler I use kernel interaction like:

var kernel = IPython.notebook.kernel;
kernel.execute('onClick()');         

Callback is called successfuly (I checked by beep), but print produce no output in cell, where by button is displayed. So I suppose there should be some magic (like everyting in Python world!) to acceess print area, could you please help me to cast it?

Answer 1

The key is to use Output widget

from ipywidgets import widgets
from IPython.display import display, HTML

out = widgets.Output()

def OnClick():
    with out:
        print 'QQQ'

display(HTML('<a onclick="IPython.notebook.kernel.execute(\'OnClick()\')">Click!</a>'))
display(out)