From the draft-js documention, one can (in vanilla React, with no typescript) setup the Draft-js environment thus, noticing that the onChange property can be declar
private onChange = (editorState) => this.setState({ editorState } as MainState)
just in the body of the class, where you define other class properties. I dunno, which version you're running, but this code totally works in ES2015 and TypeScript 2.0.10