Simple Javascript doesn't work in Dash...hmmm

I’m trying to trigger this javascript with an onclick event in page element.

Here’s the javascript, which lives in a separate file in the assets folder:

function myFunction() {
alert(‘If you see this alert, then your custom JavaScript script has run!’);
document.getElementById(“atcharttype”).innerHTML = “Paragraph changed!”;

The page element is here:

        dcc.Dropdown(options=dropdownlistcharts, style={'width':'220px'},id='atcharttype', onclick=, value=defaultchart),
    ], className="two columns"),

And what I’d like to add is the html equivalent of “onclick=myFunction()” to dcc.Dropdown.

Any ideas how to solve this?