Alert and Toast timeout

[tcbegley]

This PR addresses #190, adding a duration prop to both Alert and Toast allowing user to specify a timeout in milliseconds after which the alert or toast is dismissed.

[tcbegley]

This can be tested by installing the pre-release

pip install dash-bootstrap-components==0.7.1rc3

Here's a simple example app for testing:

import dash
import dash_bootstrap_components as dbc
from dash.dependencies import Input, Output, State

app = dash.Dash(external_stylesheets=[dbc.themes.BOOTSTRAP])

app.layout = dbc.Container(
    [
        dbc.Button("Toggle alert", id="alert-button"),
        dbc.Button("Toggle toast", id="toast-button"),
        dbc.Alert(
            "This is an alert",
            duration=3000,
            is_open=True,
            id="alert",
            dismissable=True,
        ),
        dbc.Toast(
            "This is a toast",
            header="I will dismiss",
            duration=3000,
            id="toast",
            is_open=True,
            dismissable=True,
        ),
    ]
)


def toggle(n, is_open):
    if n:
        return not is_open
    return is_open


app.callback(
    Output("alert", "is_open"),
    [Input("alert-button", "n_clicks")],
    [State("alert", "is_open")],
)(toggle)

app.callback(
    Output("toast", "is_open"),
    [Input("toast-button", "n_clicks")],
    [State("toast", "is_open")],
)(toggle)


if __name__ == "__main__":
    app.run_server(debug=True)

@happyshows if you have a chance to try this out and let me know what you think that would be much appreciated