const regex_alphanumeric = /^[a-zA-Zd]*$/;
console.log(regex_alphanumeric.test('a'));
console.log(regex_alphanumeric.test('1'));
console.log(regex_alphanumeric.test('!'));
type MarkerTime =`${number| ''}${number}:${number}${number}`
let a: MarkerTime = "0-00" // error
let b: MarkerTime = "0:00" // ok
let c: MarkerTime = "09:00" // ok