Try mx in the browser

// Edit, then press Run (Cmd/Ctrl+Enter). The preview also reruns as you type.
// console.* calls in the preview land in the Console panel.

define('counter', {
    $({ count = 0 }) {
        return [
            mx.h2('Counter'),
            mx.p({ style: 'font-size:48px;font-weight:700;margin:8px 0' }, count),
            mx.button({
                onclick: _ => {
                    console.info('clicked, count is now', count + 1);
                    this.$({ count: count + 1 });
                }
            }, 'Increment')
        ];
    }
});

document.getElementById('app').render(mx.counter());