default selection when render

hi webix Team,
I have a datatable,I want to select its 1st row by default on after render,but without using webix.once with event “onAfterRender”.
https://snippet.webix.com/yubnfaw7

only after appearing data on datatable,my code of default selection should run

The best way is to use the readyhandler function: it runs only when the data is loaded for the first time and the widget is ready to display it: Code Snippet

yes,but in case my grid data is changing depends upon the tree item i have click then what should i do?
And it is possible to write default selection code on tree event i.e “onItemClick” ,but this cause a problem when i have too much data to load on dom,

https://snippet.webix.com/6522abzn

Then the onAfterLoad event will be better for you: it fires each time the data is loaded: Code Snippet

Thanks @Helga it works