State.init({ k: 0 }); const incK = () => { State.update({ k: state.k + 1 }); }; return ( <div> root: {props.i} child: {props.j} grandchild: {state.k} <br /> <button onClick={() => { State.update({ k: state.k + 1 }); }} > grandchild + 1 </button> <br /> <button onClick={() => props.incrementparent()}>child + 1</button> <button onClick={() => props.incrementself(incK)}> grandchild + 1 (grandchild callback) </button> </div> );