Output Callback in JupyterLab Extension

Widgets
,
1

Hey there,

I am writing a custom JupyterLab extension that should receive a callback whenever an output changes.

For example, the following code creates a simple button that increases a counter and prints the current count to the output.

import ipywidgets as widgets

output = widgets.Output()
button = widgets.Button(description="Counter")

counter = 0

def handle_click(button):
    global counter
    counter += 1
    with output:
        print(counter)
        
button.on_click(handle_click)

display(button)
display(output)

image

In the extension, I want to access the output widget to listen to changes.
Currently, I can get the actual code cell output, which is just the widget object, as shown in the following image:

image

Is there a possibility to get a callback based on this information (e.g., model id)?
Maybe using the module @jupyter-widgets/base? I did not find any documentation for this module.

Best regards,
Paul