onChange

fires when the value of the control is changed

void onChange(){ ... };

$$("my_input").attachEvent("onChange", function(newv, oldv){
    webix.message("Value changed from: "+oldv+" to: "+newv);
});

Details

The function executed on this event, takes two arguments - newv and oldv that correspond to the initial control value and the newly set one.

The event handler to the onСhange event can also be attached inside the on property of the related control:

{
  view:"some",
  // ..config
  on:{
    onChange(newVal, oldVal){
        // ...your handler
    }
  }
}