Question: I'm editing an .ipynb file in VS Code using the Jupyter Notebook extension. I can't seem to figure out how to collapse (or expand) cells.

Can someone explain to me how to do this (using hotkeys or not using hotkeys), or give ideas for what I might be doing wrong?

I tried each of the hotkeys shown below, under three sets of conditions: 1. with the blue vertical bar on the left-hand side of my cell input selected, 2. with the blue vertical bar on the left-hand side of my cell output selected, 3. with my cursor in my cell input.

[!["Notebook: Collapse Cell Input" and "Notebook: Collapse Cell Output", with default bindings](https://i.stack.imgur.com/Rxg85.png)](https://i.stack.imgur.com/Rxg85.png)

Answer: 
Currently, the use of this function is not supported in Jupyter of VS Code, you could refer to this link: [Jupyter notebook cell code folding and output view expanding request](https://github.com/microsoft/vscode-jupyter/issues/1629).

Also, please try to use "[Visual Studio Code Insiders](https://code.visualstudio.com/insiders/)", right-click in the cell of Jupyter, and select "`Collapse Cell Input`" or "`Collapse Cell Output`":

before:

[![enter image description here](https://i.stack.imgur.com/dBNeq.png)](https://i.stack.imgur.com/dBNeq.png)

after:

[![enter image description here](https://i.stack.imgur.com/BCgcs.png)](https://i.stack.imgur.com/BCgcs.png)
In my VSCode insiders build version 1.61.0, its working.

What's working ->

```
 a) One shot expand/collapse all cells(code/output) in '.ipynb'(notebook)
 b) Single cell code/output expand/collapse in '.ipynb'(notebook)
 c) code folding in `.py` file with `#%%` (hierarchy style)

```

1. for `.ipynb` (your requirement)

There is keybinding available: `jupyter.notebookeditor.expandallcells/collapseallcells`

what it does?

```
        Expands/collapses all cells in one shot

```

Find this setting->

```
     Top menu File->Preferences->Keyboard Shortcuts
     In search("Type to search in keybindings"...top side) 
     type "Notebook Expand" or "Notebook Collapse", check out:

             Notebook: Expand/Collapse All Cells, 
             Notebook: Expand/Collapse Cell Input and 
             Notebook: Expand/Collapse Cell Output

     Its possible to expand/collapse single/all cells with these shortcuts keys.

```

To make this answer complete (others have answered)->

```
    1.  double click gutter area (immediate space on left side of code cell) to Expand/Collapse cell (code/output)

    2.  right click on gutter area to get Expand/Collapse cell (code/output)

```

2. Detailed post for '.ipynb' and '.py' [here](https://medium.com/@vickytrulite/vs-code-for-python-data-science-5a10f6c48cf5)