Code

<div id="entry-listen-events"></div>

const app = Redactor('#entry-listen-events', {
    events: {
        'editor:focus'() {
            console.log('editor:focus');
        },
        'blocks:change'() {
            console.log('blocks:change');
        }
    }
});

You can also subscribe after init:

app.on('editor:change', () => {
    console.log('editor:change');
});