Feature Request: file upload activity indicator

[shitian-ni]

When uploading files using jupyter notebook, nothing happens when I click on the blue Upload button after selecting files until upload is finished.
It would be great if there are "Uploading" indicators showing for example "3.3 MB / 12.7 MB" or just a progress bar or a loading indicator.

[hendrixet]

Hi, team ["Hip","Hip"] will get started on implementing this feature for you.

[hendrixet]

@takluyver hi you were able to help us on our last issue - do you have any advice as to where we should get started at looking to implement a progress bar in the source code?

Thanks in advance for any help

[takluyver]

PR #3373 is changing the JS upload code, so looking at that might help you see what's going on.

[hendrixet]

We were going to start looking in the /notebook/notebook/static/tree/js directory