Loading indication in dash app

A very simple port of nprogress.js library for the Plotly Dash ecosystem. It adds a slim progress bar and a spinner to indicate loading state in a dash app based on the number of pending callbacks. The color of the progress bar changes if any callback fails.

Just include the js library in your dash app and you are good to go.

from dash import Dash external_scripts = ["https://unpkg.com/dash.nprogress@latest/dist/dash.nprogress.js"] app = Dash(__name__, external_scripts=external_scripts) Customization

You can customize the color of normal and with-error progress bar by adding a css file in your dash app with following contents:

:root { --nprogress-color-good: green; --nprogress-color-bad: #ff00ff } TODO Make it work smoothly with long callbacks.