leevigraham said over 1 year ago on Hotwire Modals :
this.element.setAttribute("data-action", "click->turbo#click")

This will overwrite any other actions. 

Maybe the following would be safer? 

connect() {
    const oldAction = this.element.getAttribute('data-action') || "";
    const newAction = oldAction + " click->turbo#click";
    this.element.setAttribute('data-action', newAction.trim())
}