Calling external javascript functions in clientside callbacks

Dash Python
1

Hi,

I’ve been playing around with clientside callbacks today (to hopefully attach to wasm runtime). However, importing external javascript in any of my files in /assets will cause the following error:

Cannot read properties of undefined (reading ‘*’)

where * is the name of the js-defined callback. Is there a possibility to statically (once) import js-functions from other files and call them from the clientside callback function?

My /assets/custom-script.js looks like

import * as external from "./external"

window.dash_clientside = Object.assign({}, window.dash_clientside, {
    clientside: {
        call_greeting: function(name) {
            return external.greet(name);
        }
    }
});

Dynamic imports almost works though (allowing promised values as of Dash 2.4?)

window.dash_clientside.clientside = {
    call_greeting: function(name) {
        return import("./external").then((module) => {
            return module.greet(name)
        })
    }
}

However, using such dynamic import, the wasm runtime would somehow be started at each function call, which probably would be excessive?

Thanks!

1 Like
2

I’m also looking for a solution to this, have you found something? I have a few things I’d like to use in my clientside callbacks, but i currently don’t know how to. Also, do you know if i have to import Plotly? I want to use Plotly.relayout for my application.

3

Hello @Isisgv,

It is possible to import the javascript files as modules, what you need to do is create a static directly, then load the file into that directly.

Then in the app, declare the external scripts like so:

external_scripts=[{'src':'../static/mycustom.js','type':'module'}]

This will import it as a module and not a regular script. :slight_smile:

When using Dash and a dcc.Graph, you do not need to import Plotly, as it is already included. :slight_smile:

1 Like
4

Is this also possible with other external resources like scripts and functions i havent made myself,but which can be imported in your usual js scripts?

5

@Isisgv,

Yes, any scripts can be imported. Just be sure that you trust the source.

1 Like
6

great! thank you :))