WebComponent Extensions

You can think of the WebComponent pane as a HTML pane that supports bidirectional communication and large data transfer. You can use the WebComponent to quickly plugin web component or javascript libraries.

For example you can use the WebComponent pane to plug in your favourite set of widgets. For example if the DataFrame pane or widget is not enough for your use case, then plugin an alternative grid.

For an introduction to web components see Web Components: the secret ingredient helping Power the web.

The WebComponent is currently distributed via the awesome-panel-extensions package. But it is also on the roadmap for Panel. So we need your help to identify bugs and improvements or suggestions for improving the api. You can contribute your comments and suggestions via Github PR 1252.


In this example we will develop a mwc-button. It’s based on the Material Design Specification and is a part of the MWC library of layouts and widgets.

You will need to install the required packages via pip install panel param awesome-panel-extensions.

We will start by importing the dependencies

import panel as pn
import param
from awesome_panel_extensions.web_component import WebComponent

Then we define the MWCButton.

MWC_ICONS = [None, "accessibility", "code", "favorite"]

class MWCButton(WebComponent):
    html = param.String("<mwc-button></mwc-button")
    attributes_to_watch = param.Dict({"label": "name", "icon": "icon", "raised":"raised"})
    events_to_watch = param.Dict({"click": "clicks"})

    icon=param.ObjectSelector(default="favorite", objects=MWC_ICONS, allow_None=True)
    clicks = param.Integer()

    height = param.Integer(default=30)

mwc_button = MWCButton(name="Click Me!")

The key part to notice is that we configure the label, icon and raised attributes of the mwc-button to the name, icon and raised parameters of the MWCButton.

The we need to include the .js and .css files needed for the mwc-button. Currently panel.extension does not support importing module .js files. So we just use an invisible HTML pane.

<script type='module' src='https://www.unpkg.com/@material/mwc-button?module'></script>
<link href='https://fonts.googleapis.com/css?family=Roboto:300,400,500' rel='stylesheet'>
<link href='https://fonts.googleapis.com/css?family=Material+Icons&display=block' rel='stylesheet'>
:root {
    --mdc-theme-primary: green;
    --mdc-theme-secondary: purple*;
extensions_pane = pn.pane.Markdown(MWC_EXTENSIONS, height=0, width=0, sizing_mode="fixed", margin=0)

Then we define the app

settings_pane = pn.Param(
    mwc_button, parameters=["name", "icon", "raised", "height", "clicks"]
app = pn.Column(
    extensions_pane, mwc_button, settings_pane

and finally we can panel serve the app.

../../_images/webcomponent-example.gifMWC Button Image

Reference Guide

Click the links below to get a deeper understanding of the WebComponent.

More Examples