change
fires on changing the value of a control
change: (value: object) => void;
Parameters:
value: object- the current value of the control
Example
form.getItem("avatar").events.on("change", value => {
    console.log("change", value);
});
fires on changing the value of a control
value: object - the current value of the controlExample
form.getItem("avatar").events.on("change", value => {
    console.log("change", value);
});