let sidebar = new w2sidebar({

    name : 'sidebar',

    img  : 'icon-page',

    nodes: [

        { id: 'id-1', text: 'Level 1' },

        { id: 'id-2', text: 'Level 2' },

        { id: 'id-3', text: 'Level 3' }

    ],

    keydown: function (event) {

        console.log('Custom keydown event.');

    }

});

​