onBeforeRender of AtomRender, Events Webix Docs

occurs immediately before the component has been rendered

boolean onBeforeRender(object data);

data

objecta object with data that is used for rendering

boolean

returning false will prevent the component from rendering

some.attachEvent("onBeforeRender", function(data){
    //... some code here ...
});

Details

Returning false from the event handler will block further processing.