Promisified Conditional setState

set-state.js

// @flow

import {curry} from "flow-static-land/lib/Fun";

import type {ComponentType, ElementRef} from "react";

type State = Object;

type Updater<Props: Object> = (prevState: State, props: Props) => State;

const setState = <Props: Object>(
  updater: Updater<Props>,
  component: ElementRef<ComponentType<Props>>,
  newProps?: Props // to be used in componentWillReceiveProps
): Promise<ElementRef<ComponentType<Props>>> =>
  new Promise(resolve => {
    const newState = updater(component.state, newProps || component.props);

    if (newState === component.state) {
      resolve(component);
    } else {
      component.setState(newState, () => resolve(component));
    }
  });

export default curry(setState);

@mgtitimoli very nice!

What about adding a couple of usage samples and even create an npm package out of it?