Stimulus.js driven confirmable submit button

confirm-submit.html

<button type="submit"
        class="btn"
        data-controller="confirm-submit"
        data-confirm-submit-confirmation-label-value="Are you sure?"
        data-confirm-submit-warning-class="btn--warning"
        data-action="click->confirm-submit#click">
    Submit
</button>

confirm_button_controller.js

import { Controller } from 'stimulus'

export default class extends Controller {

    static classes = [ 'warning' ]
    static values = { confirmationLabel: String }

    connect() {
        this.confirmed = false
    }

    click(event) {
        if (false === this.confirmed) {
            event.preventDefault()
            this.confirmed = true
            this.element.classList.add(this.warningClass)
            this.element.innerText = this.confirmationLabelValue
        }
    }

}