onChange event should not fire for programmatic changes

[broofa]

Start with a Component that updates props state asynchronously when form values change, something like this:

function MyFormThing(props) {
  function handleChange(formState, isChanged) {
    console.log('isChanged:', isChanged)

    // (trigger async action that changes `props.foo`, below)
  }

  return (<Form onChange={handleChange}>
    <Input value={props.foo} />
  </Form>);
}

Then type something into Input field and hit TAB or whatever to cause the onChangeevent to fire. Notice the log output will be:

isChanged: true
isChanged: false

onChange appears to be getting called a second time, when the form rerenders as a result of the props changing. That should not happen - programmatic changes to form values should not trigger onChange events.

(Note: That Formsy is passing an isChanged argument to the event handler is conceptually bizarre. Why is onChange being called if nothing has changed?)

[rkuykendall]

So in summary, onChange should only fire if the values differ. This seems like something we could probably write a test for and then implement internally without breaking anything or changing the API at all. Unless I'm missing some complexity here, very open to contributions.

[broofa]

[Closing out issues I authored that appear to be stagnant.]