let handleOnChange = ( email ) => {
// don't remember from where i copied this code, but this works.
let re = /^(([^<>()[].,;:s@"]+(.[^<>()[].,;:s@"]+)*)|(".+"))@(([[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}])|(([a-zA-Z-0-9]+.)+[a-zA-Z]{2,}))$/;
if ( re.test(email) ) {
// this is a valid email address
// call setState({email: email}) to update the email
// or update the data in redux store.
}
else {
// invalid email, maybe show an error to the user.
}
}