Array of event handlers. There is no need to change this array directly. You should use .on() method to add event listener and .off() to remove it. However, it might be useful to iterate the array to see what event handlers have been added. let layout = new w2layout({ name: 'layout', panels: [ { type: 'top', size: 40 }, { type: 'preview', size: 200 } ] }) // add event listener for all events layout.on('*', event => { console.log(event.detail, event) }); // iterating through event handlers for (let i in layout.handlers) { console.log(layout.handlers[i]) }