A way to figure out which state or props changed in any react component.

whatHasUpdated.js

const whatHasUpdated = (instance, props, state) => {
  const changed = (obj, comparedTo) => Object.keys(obj).reduce((memo, key) => {
    if (comparedTo[key] !== obj[key]) {
      memo.push({
        key,
        old: comparedTo[key],
        new: obj[key],
      });
    }

    return memo;
  }, []);

  if (process.env.NODE_ENV === "development") {
    const changedProps = changed(props, instance.props);
    if (changedProps.length) console.info(...changedProps);
    const changedState = changed(state, instance.state);
    if (changedState.length) console.info(...changedState);
  }
};