state: State = { someProperty: '' }

onChange = (name: keyof State) => (e: React.FormEvent<HTMLInputElement>) => { const newValue = e.currentTarget.value; this.setState({name: newValue}); } }

render(): JSX.Element { return ( <div> <input type="text" onChange={this.onChange('some-name-not-in-state')} /> </div> ); }