How can I get the `hoverData` object from `.html` file?

Dash Python
1

I’m trying to implement a simple version of dash to Rust, but being new to front-end programming , I’m stucking the following situation.
In Python:

from dash import Dash, dcc, html, Input, Output, callback

import plotly.express as px

external_stylesheets = ['https://codepen.io/chriddyp/pen/bWLwgP.css']

app = Dash(__name__, external_stylesheets=external_stylesheets)
fig = px.scatter(x=["a", "b", "c"], y=[1, 2, 3])

fig.update_traces(marker_size=20)

app.layout = html.Div([
    dcc.Graph(
        id='basic-interactions',
        figure=fig
    ),
    html.Div(id="hover-data")
])


@callback(
    Output('hover-data', 'children'),
    Input('basic-interactions', 'hoverData'))
def display_hover_data(hoverData):
    # return json.dumps(hoverData, indent=2)
    return str(hoverData)


if __name__ == '__main__':
    app.run(debug=True, port="8082")

The generated callback function display_hover_data accepts an object of hoverData, which must be generated by some information lieing in the .html file. If I wanna to implement similar callback function in other language, I must extract the same inforamtion and then make an object hoverData firstly. But how can I extract the information from the .html file, where the information lies? I tried to read the source code from package Dash.py, but I still can’t figure it out. Can anyone help me?

2

I might be mistaken, but I think you will have to do this in javascript with an eventListener.

1 Like
3

But I’ve read the souce of Dash.jl, which is a package of implementing dash in Julia, it doesn’t use javascript.

4

May I ask where is the code about getting the hover information and make the object hoverData lies in the package Dash.py?